The most common frequency adverbs in English are:
Always
Frequently

Usually

Often

Sometimes

Occasionally

Seldom

Rarely

Never
100% of the time
about 90% of the time

about 80% of the time

about 70% of the time

about 50% of the time

about 40% of the time

about 20% of the time

about 10% of the time

about 00% of the time

Note: The percentages here are rough estimates only.

Frequency adverbs can be placed at various points in the sentence, but are most commonly used before the main verbs and after be verbs.

I always come to work on time.
They are seldom home when we call.

He's usually eating breakfast at this time.

She's never been to Maine.

A: Do you come here often?

B: Yes. I'm here occasionally.

A: What do you usually do here?

B: Sometimes I just sit and ponder the meaning of life.

Note: The adverbs seldom, rarely, never and hardly ever are considered negative.

A: Do you always carry a briefcase?
B: (Yes,) I usually do.

No, I usually don't.

No, I rarely do.

No, I hardly ever do.

Other frequency adverbs and expressions are as follows:

Every day/week/month
Every other day/week

Once a week/month/year

Twice a year/day, etc.

(Every) once in a while

Every so often

These expressions are used at the beginning and end of sentences, not before main verbs.

Every once in a while I visit my grandmother in Minnesota.
I visit my grandmother in Minnesota every once in a while.

I every once in a while visit my grandmother in Minnesota. (Incorrect)

Regularly
Normally

Traditionally
(according to schedule)
(commonly nowadays)

(commonly in the past)

These words can come at various points in the sentence.

I regularly floss my teeth.
I floss my teeth regularly.

Traditionally, that was considered child's play.

I normally get up around 6 o'clock.

Normally, I get up around 6 o'clock.

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