Articles

The definite article (the) is the most commonly used:

When there is only one of something, either in existence or in a particular context. I'd like to speak with the manager.
When something is mentioned again. I've read three novels and two plays by Camus. What did you think of the plays?
When both listener and speaker know what is being referred to. Hurry up! The film starts in 5 minutes.
When talking about a specific aspect of something, where the noun is followed by of. We're studying the history of architecture.
To speak generally about certain groups of singular countable nouns. Interventions: The mobile phone is thought to pose a serious threat to health. Animal species: The wale is still hunted by some countries such as Japan.
With adjectives referring to general classes of people, ex: the homeless, the blind, the rich, ...
With superlatives. Who is the greatest footballer in the world.
With musical instruments. I'd love to learn to play the piano.
With types of transport which have a fixed timetable. Shall we get the bus or take a taxi?
With some countries, ex: the USA, the UK.
With oceans, montain ranges, deserts, rivers, etc. The Atlantic, the Pyrenees, ...
With some geographical areas. We're going to the mountains rather than the coast.


The indefinite article (a/an) is most commonly used:

When a singular countable noun is mentioned for the first time. A man went into a bar with a fish.
When referring to any one of several things. It's quiet in here. Shall I put a record on?
When talking about a person's job. My father is a nuclear scientist.
With some numbers, ex: a hundred and one dalmatians, a thousand people, ...
When it means "per" in some expressions, ex: twice a day, 50 miles an hour, ...


No article is used:

When referring to nouns in a general sense. Plural countable nouns. Do you think computers will replace teachers? Abstract nouns. We sang songs of love and peace. Other uncountable nouns. Alan won't eat cheese or meat.
With most streets, towns, cities and countries. I went to Bond Street when I was in London.
When a town's name is used with a building, ex: Luton Airport, Cambridge University.
In many common expressions, ex: to go home, to go to work/school/..., to be at home/..., to be in hospital/...

Monty Python - Dead Parrot

Monty Python - Job Interview

Comparatives and Superlatives

FORMS

Regular one-syllable adjectives:
- add -er and -est to the adjective: cheap(Adjective)-cheaper(Comparative)-the cheapest(Superlative)
- add -r and -st to adjectives ending in -e: late(Adjective)-later(Comparative)-the latest(Superlative)
- double the consonant of adjectives ending in a short vowel and a consonant, and add -er and -est: thin(Adjective)-thinner(Comparative)-the thinnest(Superlative)

Regular adjectives with more than one syllable:
- use more and most in front of the adjective: sincere(Adjective)-more sincere(Comparative)-the most sincere(Superlative)
- change -y to -i and add -er and -est to adjectives ending in -y after a consonant: happy(Adjective)-happier(Comparative)-the happiest(Superlative)
- a limited number of two-syllable adjectives can form the comparative and superlative in two ways:  stupid(Adjective)-stupider/more stupid(Comparative)-the stupidest/the most stupidest(Superlative) 
- most adverbs form their comparative and superlative with more and most: quietly(Adverb)-more quietly(Comparative)-the most quietly(Superlative)

Irregular forms:
- adjectives: good/better/the best - bad/worse/the worst - far/further/the further - old/older/the oldest
- adverbs: well/better/the best - badly/worse/the worst - little/less/the least - much/more/the most
- determiners: little/less/the least - few/fewer/the fewest - much/more/the most


USE

To talk about people or things that are different in some way we use:
- Comparative forms of adjectives/adverbs + than: I think listening is more difficult than reading.
- Superlative forms of adjectives/adverbs: That's the nicest thing you've said to me all day.
- Less...than and the least: That's my least favourite track on the album.

As .. as
For people or things that are the same in some way we use as + adjective/adverb + as: She's as intelligent as her brother.
So can replace the first as in negative sentences: It's not so difficult as I thought it would be.
The same + noun + as: My mum's the same age as my dad.

The + comparative, the + comparative:
We use this structure for things which occur together: The more money I have, the faster I spend it.

Gerunds and Infinitives

The GERUND is used in the following cases:
- As
Subject: Reading in the car makes me feel sick.
Object: I find shopping for clothes really boring.
Complement of a clause or sentence: My favourite sport is swimming.
- After prepositions.
I'm not very good at making things.
NB: to is a preposition in the following verbs: look forward to; get used to.
- After certain verbs
Charles suggested going for a picnic.


The INFINITIVE with TO is used:
- To express purpose
I'm learning English to help me get a better job.
- After many adjectives: surprised, delighted, disappointed, easy, happy, important, lucky, necessary, normal, possible.
I was surprised to hear he had failed the exam.
- After certain verbs.
He offered to give her a lift, but she decided to go by train instead.

Gerunds and infinitive after verbs:
- Verb + gerund
The following verbs are normally followed by the gerund.
Certain verbs expressing likes and dislikes: adore, detest, dislike, enjoy, don't mind, can't stand.
Other verbs: admit, avoid, can't help, consider, delay, deny, feel like, forgive, give up, imagine, involve, keep, mind, miss, postpone, put off, practise, prevent, resist, risk, suggest.
- Verb + infinitive with to
The following verbs are normally followed by the infinitive with to: afford, agree, appear, arrange, ask, attempt, choose, decide, deserve, expect, help, hesiate, hope, learn, manage, offer, prepare, pretend, refuse, seem.
The infinitive with to is also used after: would like, would love, would hate, would prefer.
- Verb + gerund or infinitive
Like, love, hate and prefer are usually followed by the gerund. However, the infinitive is also possible with little, if any, difference in meaning.
Begin, start, continue and intend can be followed by gerund or infinitive with no change in meaning.
Forget, remember, go on, mean, need, regret, stop and try can be followed by the gerund or the infinitive; but with a change in meaning.
* remeber/forget + gerund: (not) to recall a previous action
   remeber/forget + infinitive: (not) to remember what you have to do
* go on + gerund: to continue with the same activity
   go on + infinitive: to change to a different activity
* mean + gerund: to involve
   mean + infinitive: to intend
* need + gerund (passive meaning)
   need + infinitive (active meaning)
* regret + gerund: to be sorry for a previous action
   regret + infinitive: to be sorry for what you are going to say
* stop + gerund: to stop an activity you are doing
   stop + infinitive: to stop doing one thing in order to do another
* try + gerund: to experiment in order to see what will happen
   try + infinitive: to make an effort; to attempt to do something.

Indirect ways of asking questions

A number of expressions can be used to ask questions in a more indirect way. Indirect questions can sound more polite than direct ones.
Could you tell me where she studies?
We'd like to know when you first started singing?
When asking indirect questions the same word order is used as when we make statements. The auxilary verbs, do, does and did, are omitted.
If or whether is used if there is no question word such as where, what, why, when, who and how.
Could you tell us if/whether you are married...

Be used to / Get used to + noun or gerund.

Be used to + noun or gerund means "be accustomed to"
She's a nurse so she's used to seeing sick people.

Get used to + noun or gerund means "become accustomed to"
I want to leave Athens; I can't get used to the heat.

Habitual behaviour in the past

The past simple is used for regular actions or habitual behaviour in the past, often with a frequency adverb:
I hardly ever went away on holiday when I was young.

Used to + infinitive is used to refer to past habits and situations which no longer occur or exist now:
We used to have a dog, but he died last year.

Note: the negative and question forms:
I didn't use to like pizza. Where did you use to study?

Note: use to cannot express present habitual behaviour. I usually (not use to) play basketball once a week.

Would + infinitive is used to refer to past habits, but not past situations:
Habit: My mother would often read to me when I was a young boy.
Situation: I used to (not would) have a bicycle.

Stative verbs such as have (possession), be, live, like, believe, think (= have an opinion), understand and know are not used with would to refer to the past.

Habitual behaviour in the present

The present simple is used for habitual actions or permanent situations in the present:
I go for a run twice a week.

Frequency adverbs are used to indicate how often an action occurs. They are usually placed:
Before the main verb. I never go to bed before midnight.
After the verb to be or an auxilary verb. She is very often early for work. They have rarely been seen together.
Usually, normally, frequently, sometimes, very/quite often and occasionally can also placed at the beginning of the sentence or clause. Occasionally we go out to the cinema. Note: always, rarely seldom, hardly ever and never cannot be used in the same way.

Variations:
The present continuous + always is used to talk about things which occur frequently and which the speaker finds annoying (fastidioso). He's always complaining about something!
Adjectives can be used as an alternative to rarely, normally and (not) usually. It's rare/normal/(un)usual for him to eat meat.
Tend to + infinitive is used to make general statements about the habitual actions and situations of groups of people or individuals. English people tend to drink tea rather than coffee.
Will + infinitive is used to talk about habitual behaviour. Frequency adverbs can also be added. She'll sometimes spend the whole day reading.
Keep (on) + gerund is used to talk about repeated actions, often annoying ones. Peter keeps on hitting me.

Sounds and spelling

Here are two files where you can see the 44 english phonemes. Then, I recommend you open the web site down here, write the different words from these files and finally listen the correct pronunciation.

http://www.howjsay.com/

Bad Pronunciation

Here are five sequences of celebrities speaking with bad pronunciation of English. Not for sensible people. With all my love, this is because I want to improve my, our and their English. This is for learn how we mustn't speak. :P Soon, some more! Enjoy it!

Emilio Botín

El príncipe gitano

Jesús Gil

Zapatero

Francesc Roses

Games

You will find free word games in these links, with different levels:

http://dictionary.reference.com/fun

http://www.learn-english-today.com/wordgames.html

http://www.shockwave.com/online/word-games.jsp?filter=online&col=releaseDate&dir=desc

http://www.stickyball.net/games-and-activities.html

http://www.eslgamesworld.com/

http://www.englishclub.com/esl-games/

http://gamestolearnenglish.com/

http://www.manythings.org/mq/

Dictionaries

Three dictionaries very complete...

http://dictionary.reference.com/
http://oxforddictionaries.com/
http://dictionary.cambridge.org/