Some tips:
Match the hatch is most improtant, turn over a rock look at what nymps are in there and match it.
How your fly hits the water, you can't have it smack down it has to have a nice soft puffy landing just gently land if you don't have that right your sunk to start. Dry flys that is.
Learn the roll cast, there arnt many times you will have the room to do the reg back and forth cast to get distance with trees etc. The roll cast comes in very handy.
Don't wear chest waiders if your a rookie as I was told that many people drown when they first start out maybe thats a myth but thats what I was told but then again I was kid back then not now hehehe.
There used to be something called gymp you rubbed onto dry flies to keep them floating on top, u can use margarine if you don't have ought else.
Tiny clean knots of course your fishing tiny baits u need to have clean tidy knots.
Prob most important, I hate hats but when I fly fish wear a dam hat not a ball cap a proper cowboy had or same shape TRUST ME it will save your ears at least once hahahahah.
l8r hope it helps.