How often
The frequency scale for habits, plus nando mo for one thing repeated again and again. Every one of these goes ahead of the verb phrase it describes.
mainichi
every day
毎日 まいにち
Says something happens every single day. It is the backbone of talk about routines.
mainichi aruite kaeru.
I walk home every day.
毎日歩いて帰る。
mainichi aruite kaerimasu.
I walk home every day.
毎日歩いて帰ります。
The same mai- gives maiasa (every morning), maiban (every night) and maishuu (every week).
itsumo
always, usually
いつも
The default word for habits and for doing things as usual. It sits at the top of the frequency scale.
itsumo aruite kaeru.
I always walk home.
いつも歩いて帰る。
itsumo aruite kaerimasu.
I always walk home.
いつも歩いて帰ります。
itsumo no means 'the usual' (itsumo no mise = our usual place).
yoku
often
よく
The everyday word for 'often', used before any verb to describe a habit (yoku iku).
yoku aruite kaeru.
I often walk home.
よく歩いて帰る。
yoku aruite kaerimasu.
I often walk home.
よく歩いて帰ります。
It is the same word as 'well' (yoku dekita = well done), and yoku wakaranai means 'I'm not really sure'. yoku nai (not good) and yokatta (that's good) come from ii, not from this 'often'.
tokidoki
sometimes
時々 ときどき
The middle of the frequency scale, for things that happen now and then.
tokidoki aruite kaeru.
I sometimes walk home.
時々歩いて帰る。
tokidoki aruite kaerimasu.
I sometimes walk home.
時々歩いて帰ります。
tama ni
once in a while
たまに
The low end of the scale, one step below tokidoki. Very common in casual talk about habits and treats.
tama ni aruite kaeru.
I walk home once in a while.
たまに歩いて帰る。
tama ni aruite kaerimasu.
I walk home once in a while.
たまに歩いて帰ります。
tama ni wa means 'for a change, every once in a while' (tama ni wa ii ne = nice for a change; tama ni wa renraku shite = get in touch once in a while).
nando mo
over and over, many times
何度も なんども
Says the same thing happened again and again, usually in past tense (nando mo mita = I've seen it loads of times), often with a note of frustration.
nando mo itta jan.
I've told you so many times!
何度も言ったじゃん。
nando mo itta ja nai desu ka.
I've told you so many times!
何度も言ったじゃないですか。
nankai mo means the same and is just as common in casual chat (nankai mo itta jan). ichido mo + negative means 'not even once'. Don't mishear nandemo (anything): nandemo ii = anything's fine.