in general, try to play to control the pot size (keep it kind of small) when you have top pair or less. sort of player dependent, and sometimes you just have to "play poker" and exploit players who are bad or overly loose, but as a general rule, this is good.
when you have a big hand, don't get cute and slowplay to effing death like so many do, because you're burning money. build big pots with big hands, and if they have anything at all, you'll get paid off. at this level if you're losing big pots with two pair or better, you can usually just chalk it up to a cooler, unless the board is really bad. many players at 25NL will take top pair to the grave. don't make the same mistake, and you're already in good shape