If your opponent bets the pot, you have to be pretty sure that you can get some more money out of him if you hit. Still, when a player bets the pot he's often protecting his hand. The third card of a suit in this spot is a major scare card and I find it quite hard to get paid off.

Flushes are quite obvius, as opposed to straights. I would recommend calling only when you get proper odds for it. (But if you think you WILL get payed off, by all means, go for it.) What stakes do you play?

I feel like I've saved a lot of money by stopping limping Axs, especially out of position. It's also easy to his an ace and donate some money to a bigger kicker. Suited connectors can be great in the right spots (late position, cheap flop, multiway pot).