Message Board : how to play medium top 2 pair? (NL)

I have trouble with this kind of hand. I'd appreciate any comments, general concepts etc.

Here's a typical hand:

Tight table with lots of folds to PF raises and to bets on the flop (steals appear to be common). Blinds are 0.02/0.04$ (micro-NL).

I'm on the button with: 10:hearts: 8:hearts:

My stack: 90BB (everybody has me covered)

UTG+1 limps; MP limps; I limp (maybe the trouble starts here already?); SB completes; BB checks

Flop (5BB): 10:diamonds: 8:clubs: 3:diamonds:

checked to MP who bets 3BB (MP is TAG, so this might well be an attempt to steal)

I raise to 9BB (on one hand I wanted to punish a steal and also protect my hand against a flush/str8 draw, OTOH I didn't want to bet too much in case he limped with 33, 88 or even TT).

=> What should be my priority here (protect the pot against draws; extract the most out of overpairs/flopped pairs; protect my stack against a set; anything else???)? How can I accomplish that goal best?

On with the hand: all fold; MP calls

Turn (23 BB): Q:diamonds:

MP bets 20BB (Since he's an aggressive player this could be a bluff representing a flush.)

The bet size really posed a problem for me (75BB left): a smaller bet => easy call; a bigger bet => not so easy but still fold. What would you do and why?)

I don't want to spoil your thinking with telling you the rest of the hand (at least for now).

Any ideas? Am I the only one having trouble with flopped 2 pair hands?