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.