Here's a situation that comes up a lot that I'm feeling kind of lost on atm. Help me.

You're in the sb/bb with a hand like 78s or 2 other middle cards. A LP limper or 2 comes in.

For this example, you had 78s in the sb and completed after 2 limpers. Flop comes down something raggity like T83r, giving you 2nd pair/bad kicker. You bet out (this is correct?), and get one caller in the CO. What do you do on the turn when a) it's a somewhat scary card, like a J or A, when it's a rag? Your opponent is SLPP (standard PP/PS fish).

Betting out is ok. If the board had a card higher than a T, I probably check/fold.

On the turn, you must bet again.

I think it's situational.

It's highly dependent on your reads on the late position limper (or limpers, because the fewer people in the flop, the more likely you should bet). If you bet and get one call, you have to bet again on any turn.

If the turn and river go badly for you, I think check/calling the river isn't a bad idea.

If there are more people in the flop, or you have the read that you can't make LP fold, or if LP is aggressive enough to try to push you off it, check/folding the flop isn't bad either.