Buy in amount

How many times the BB do you guys reckon you should buy in for? I'm starting to think i just buy in for too little, coz if i have a couple of hands where i don't manage to get out right away post flop i can get a little short stacked, and then it is 1. hard to make much money and 2. very easy for a big stack to put you all in. I probably buy in for about 40-50xBB atm because that is all my BR really allows. But i really feel if i don't win the first pot i get somewhat committed to im pretty much f'ed if i don't top up a bit. I end up losing my entire buy in more than i should i think because it doesn't tend to cost big stacks that much to put me all in (ofc i also tend to double up quite often for the same reason).

If you think you are better than most online players, buy in for the max. If you can't afford to due to your bankroll, move down a level and buy-in full. If you do buy in short though make sure you employ short stack strategies. You no longer have implied odds with a lot of hands and can afford to stack lighter.

Do you mean like it is less profitable to play low pp's/suited connecters or something coz missing it will hurt you since you get somewhat involved in a pot that costs you a decent amount of your stack and even if you do hit a set 1/8 times it can't really pay off that much?

Basically yes. Your stack is smaller in relation to the blinds, and thus if you hit a hand that will normally stack your opponent (set vs. TPTK sometimes or set vs. 2 pair) you will not get as much. If you can win 100 BBs you can call a 4x raise easily for set value, if you can only win 30 BBs if you hit it's not profitable any more. Of course that means you don't have to worry as much about reverse implied odds, which is the direct opposite. You can afford to stack with TPTK 99% of the time because most opponents didn't call preflop with implied odds against you. Playing shortstack is actually an advantage strategy-wise, but if you are significantly better than most opponents and can be expecting to win a lot of big pots and not losing as many, playing as a big stack is probably more profitable.

Im actually tempted to try that now. Maybe something like buying in for min 4$ in .1/.2 waiting for AA/KK/QQ/AK/AQ then limping from EP and reraising all in or check raising all in on flop unless i totally missed and reraising all in preflop from LP. Would need a really aggressive table tho.

Then top up to max, after going 2.5x up, and play "proper". You really would have pretty insane implied odds coz you'll probably get your money in at 2:1 most times if you have a loose table, and will get fold equity for nothing since most likely it will be heads up come the showdown.