.this is versus a tag only and no other callers...
First of all there are always 2 players left to act, they could both call, especially if you just flat instead of 3-betting.
If you consider yourself a good post-flop player, you should consider calling/3-betting a VERY wide range in those spots, especially at these stakes, here's why:
first of all, at these stakes it doesn't really matter whether they open from UTG, UTG+1 or the CO, most players don't even look at that, all that matters is whether you have position on THEM or not.
In this case you do, now comes the second points; 3-betting or calling?
I personally 3-bet very wide (i have to warn you my pfr is somewhere 35-40'ish, I play very laggy and that may not be your style).
I do this because players raise-fold 75% at these stakes, so you'll take most of the pots down pre-flop.
Also you can put them on a perfect range after 3-betting, when they 4-bet they never
bluff (unless it's BvB) so you can just fold with marginal
hands, and go for straight value with your big hands.
If you're not a great post-flop player, don't flat pre with AQ+, QQ+.
Why not? because you're going to **** yourself up against sets, 2 pair, hands like AK with AQ and all that stuff post-flop.
Barely anyone can lay down big pocket pairs or hands like TPTK at these stakes, it's not a shame if you play 10NL, but it's better to avoid these spots.
Good luck!