I always try to play them this way...the Chris Ferguson way.
I will open up for a standard raise pre-flop with them, unless that raise has already been made, in which case I'll flat call. Unless someone's went all in and there's only two decisions to make in that position, I won't fold pre-flop with them. If they do move in, my choice depends on that person's table image.
Come the flop, if my pair is an over-pair, I'll come in for a bet. If I was the agressor pre-flop, a player with a larger overpair might think I hit the set on the flop. If I hit my set, I might check and let loose players bet into me.
If it comes overcards on the flop, I'll check and let other people take action. If a tight player comes in, I'll fold, he probably has the goods. If a loose player, or a bluff central bets, I might just flat call, thinking he's got crap.
The hardest part is not playing these cards, you've got a pair, pair can be golden tickets. The hardest part is knowing when to let middle pairs go.