When using the present simple tense, adwords of frequency are used to express 'how often' we do something. Below you will see a list of the most common adverbs in order of frequency.

always

usually
normally
generally
regularly

often
frequently

sometimes
occasionly

rarely
seldom

never

Where is the adverb of frequency placed?

Usually the adverb is placed between the subject and the verb.

I often have toast for breakfast.
I sometimes watch football.
He rarely does his homework.
They never drink coffee after 6 pm.
We normally go away in the summer.

When using the verb 'to be' the adverb is usually placed after the verb.

Paul is usually late.
David is never here.
I am always hungry!

If more than one verb is used (auxiliary verb), the adverb is placed between the two verbs.

I would usually go there.
I don't normally smoke.
The students have often complained that they receive too much homework.

Note: Exception is 'have to'. I often have to repeat the exercise.

Expressions

Every now and then
From time to time

Every day/week/month/year
Once a week/month/year
Twice a day/year
Three times a day/week/month/year

Expressions are placed at the beginning or end of the sentence.

I study English every day.
Every now and then I go to the gym.
I eat three times a day.
I go to the cinema from time to time.