Starting to learn...(sorta long)

[kingofswing]

Okay, so I just finished a two hour-ish session on Party NL25 tables and I think I'm starting to get the hang of being more aggressive. If you were to search the SSNL section for my posts, you'd find one about maybe folding set over set and another about folding a boat to a possible two card four of a kind. Now I was never actually going to fold either, but from those posts you might think I'm pretty weak. Well, that's probably a little bit true, but I am working on it. Today I ran a couple of biggish bluffs, and one got picked off (or rater the dude had two pair) and but a bunch more worked. Suddenly, even though my flopped two pair -- aces and ducks -- got rivered by a guy hitting a jack to make aces and jacks and a pair of jacks got rivered by a guy calling down with a flush draw and KQ (yup a Q), I was still able to turn a $20 dollar profit. Now some of that is thanks to doubling through with AA and KK, but nevermind.

The real important thing I think is my ability to pick spots to try to pick up pots on the turn/river with semi-bluffs. So after patting myself on the back, I've got a couple questions.

The real question I've got is I am seeming to learn that it's better to bluff your chips off than call your chips off when you know you are beat. So I think I'm getting the postflop aggression, but how do I loosen up preflop? My stats are around 17-18/3-4. It's really that 3-4 that I know should be higher. What's the best way to increase this?

Raise more unraised pots in late position with marginal holdings (like ATs, KQs,QJs, etc.)? Raise more liberally overall, even in EP?

And the second part is that what do you call preflop raises with? If a MP raises to 4xBB, right now I tend to call only with PP. I mean I raise big hands, but I shy away from calling with ATs, KQs, etc. should I be? If this guy raises 8% of flops, what should I be calling with to see a flop?

Thanks guys.