Medium pairs

One of the hands I have a love/hate relationship with is medium pairs (7-8). Very few times will you ever fold them preflop, and in a limit game, deciding rather to just call or raise isn't that hard.

But no-limit can be troublesome. Raise bigger from early position? Limp? I tend to mix up my early play, limping most of the time and raising big probably 20-30 percent of the time.
I just don't know if it's ideal. My play is based on the lose less money when your hand doesn't hit philosophy, which will happen more times than not. But it also doesn't get rid of any weak Aces or kings, making it more likely my medium pair will be out flopped.

But the limp play sometimes makes it easier to win bigger pots when your hand does hit. Let's say I have 8-8, 2nd to act, and I limp, as do 5 others. Six players total, and the flop comes A-8-3 rainbow. It's fairly obvious no one has a real strong ace, by the lack of action, but an A-8, or A-3 is possible. And any player with a decent ace will still stay. If I lead out here, I'd go about 3/4 pot-pot sized bet or more depending on the flop (rainbow, all suited, 2 suits, etc...). Bet stronger if there's two of the same suit, less if rainbowed or all the same suit. Anyone who made the nut flush will stay in, but isn't likely to be too aggressive, wanting to extract as much as he can from the board. And you want to give anyone on a flush draw the improper odds to call.  (It's amazing how many people ignore the odds and chase on the flop).

And I'm often lost on late to act preflop. If there's a 3x-5x raise in front of me, it's okay to assume my 8s are the low hand right now, but is it worth it to call the raise?
All limpers and my 8s may be good. Do I raise and how much? Ideally, I want a heads up situation, rather I create it or the initial raiser does. And if you know your opponent, and can put him on the proper hand, even if you miss your pair, can you pull off a bluff?