Help with middle Pocket Pair

[JDO]

Haven't posted in awhile but this is giving me fits lately.
In general how should I be playing a mid-level PP (say 77-TT) post flop with a not-to-scarey over card on the board (like a J or a Queen)?

I've been using a normal "thin the players" 3X BB raise preflop raise when I open, and calling when there are callers in front (is this my msitake?)

Post-flop (this applies to both situations) I bet out 1-3 to 2-3 pot but always get called.

Is this just the nature of late-night 10 dollar SnG's?

Thanks