Adverbs of frequency go before the verbs used to or have to:-

Adverbs of frequency include; always, constantly, continually, frequently, infrequently, intermittently, normally, occasionally, often, periodically, rarely, regularly, seldom, sometimes etc.

For example:

I always do my homework on time. - In this sentence always shows us the frequency (how often) I do my homework on time.
She goes out occasionally. - In this sentence occasionally shows us the frequency (how often) she goes out.

Most frequent	always
	constantly
	nearly always
	almost always
	usually
	generally
	normally
	regularly
	often
	frequently
	sometimes
	periodically
	occasionally
	now and then
	once in a while
	rarely
	seldom
	infrequently
	hardly ever
	scarcely ever
	almost never
Least frequent	never

Adverbs of frequency appear between the subject and the verb in a sentence:-

For example:

I always update the calendar at the beginning of the month.
Poetria often takes notes during the Skype sessions.

Adverbs of frequency appear after a form of the to be - am, are, is (was, were) in a sentence:-

For example:

I am never late.Skype is occasionally frustrating.
They were always noisy.

Adverbs of frequency go between an auxiliary verb and the main verb:-

For example:

Anne doesn't usually smoke.

If there are two auxiliary verbs, the adverb of frequency goes between them:-

For example:

I have never been to Asia.

The adverbs of frequency often, usually, sometimes and occasionally can go at the beginning of a sentence:-

For example:

Usually I don't give personal advice. = I don't usually give personal advice.
Occasionally we go for a drive on a Sunday. = We occasionally go for a drive on a Sunday.

Adverbs of frequency go before the verbs used to or have to:-

For example:

I always used to celebrate bonfire night.
I usually have to get up early to walk Laika.

When something happens regularly at a fixed time we can use the following as adverbs:-