I do it mostusually do it with my left hand when I'm thinking about somethings and with left hand.

I often touch my eyebrows with my middle finger, it. There's no meaning to it in Japan, but I should quitavoid doing it in a foreign country.

I do it mosmostly do it when I'm thinking about somethings and with my left hand.

I often touch with middle finger, it' has no meaning in Japan, but I should quit it in foreign country.

I do it most with my left hand when I'm thinking about somethings and with left hand.

You should move "with my left hand" to the front, so it's clear that touching your eyebrows is the action that's being referred to. Otherwise, it might be interpreted to mean that you think with your left hand (which doesn't make sense).

I often touch with my middle finger, it's. It's got no meaning in Japan, but I should quit it in a foreign country.

(1) If you're not using a conjunction between "I often touch with my middle finger" and "it's got no meaning in Japan", then it's more natural to just break it up into two sentences.
(2) Although "it's" is certainly a contraction of "it has", I think "it's no meaning" is a very awkward expression.

I do it mostthe most/ mostly when I'm thinking about somethings and with my left hand.

I often touch them with my middle finger, it' has no meaning in Japan, but I should quit (doing) it in a foreign country.

It doesn't matter if you do this in a foreign country. I don't think it's considered rude anywhere. We all have our little quirks, that's what makes us different.