I recommend picking up a copy of Collin Moshman's Sit 'n Go Strategy,
this book really helped me get started and plugged a lot of my huge leaks when I was starting out.
You should be raising pre-flop the vast majority of the time, persistently limping in with marginal hands and hoping to get lucky is not a good strategy. This is very basic but very important: when you limp/call, the only way you can win the pot is to win at showdown. However, when you bet/raise, now you have an additional way to win the pot, which occurs when all of your opponents fold.
Suited connectors look nice but when you do connect with the flop, it's probably going to be middle or bottom pair with no draws a lot of the time. The only time I would limp with suited connectors is in late position or in the SB when others have already limped in. If I decide to open a pot with these, I'm going to raise with them.
I c-bet the majority of the time, there are some situations where I may plan to do a delayed c-bet if I don't like the flop but I'm in the hand with only one villain and he/she shows weakness. If multiple opponents are in the pot and you completely miss the flop, usually a c-bet is just wasting chips here. There's an art to c-betting, you can do it too little and it can also get you into trouble if you do it too much.
are important everywhere, if you're constantly chasing 8:1 draws with 3:1 pot odds you're going to lose in the long run.
Lastly, limp/folding a lot makes you look like you're playing scared and this is the kiss of death at a poker table, because people will run all over you.