sounds like a super common error of playing way too tight
raising 4bb and folding overall sounds like the worst thing you can do. Quick fix would be to raise 2.2x the BB and fold to a shove, that will save you thousands of chips straight off the bat.. you're welcome.
But yeah you are basically asking us to write a book. As a general sort of strat you want to open up a litlte more early, esp in position and esp vs fish. In the mid to late game you really want to crank up the aggression and start 3bet jamming, min raising to steal and jamming 12bb and below stacks with way more hands than just pairs
If you ever get into a hand you are unsure about, post it in the HA section of the forum. Apart from that, getting a subscription to a training site will help you alot, so will purchasing SNG specific books.