In cash games, I prefer fixed limit for the variance control. It is a different game than NL, so you need to adjust if you don't play fixed much. In limit holdem, drawing hands are more valuable, and, with a good draw, you can often simply call it down till you get there; if you have AA or KK, that feels frustrating, but that is limit. And, no, you can't push the drawing hands out of the pot-- but when you have one, you like that. (I have been playing NL low/micro to do the Academy challenges, and that has sometimes been profitable even at those levels, but those nasty beats get painful in NL.) You can survive a horrible beat in fixed limit and move on. The beat can be only cards, and can be relatively light on your stack, so it can be a lot easier to deal with.
I play tight out of position, and slightly looser in position.
Never call preflop -- if you want to play a hand, either raise or fold.
Never limp with AA. (I hate saying never, but, seriously, don't do it.)
Position is huge. Getting a sense of the other players' ranges and willingness to fold is huge.
I strongly suggest playing the FT Academy challenges. PreFlop Play is hugely helpful, as, if you complete the challenge the permitted 10 times, you will have learned a lot about the value of the standardized raise, and of raise-or-fold. You will become
trained, like it or not. And you will see how well it works.
Leave your ego and emotions somewhere else. If you tend to go on tilt, cash tables can gut your
bankroll.
Practice solid, disciplined bankroll management. There is sadness in moving down in levels, after a bad string, and the potential profits are sadly diminished. Screw it-- the potential losses are also diminished.
Never put your whole wad on a table. Never. It helps immeasurably with tilt is you have a good cushion to land on when the inevitable nasty beat hammers you. Say you lose $10 (your stack) on one hand. If that's half your bankroll, it's like a punch to the gut. But if your overall bankroll is $500, it feels like barely a scratch. Yeah, the beat registers, but it does not kill you. It's a blip.