when drift fishing i know i have had more than a few fish on.sometimes i can feel the bite

sometimes i cant I need to learn how to feel the bite any hints. also when i have a fish on
i always lose them in the first few seconds how do i properly set the hook and are my hooks
to small i use a 4 or a 2 should i use a treble hook or a bigger hook.
please help i really want to catch one i see other people do it and i am getting flustered