Aces are the absolutely nuts pre flop. That's the first thing to know about aces.
If you're playing
freerolls, microstakes or even small stakes, pre flop you should always raise for sheer value pre flop no matter what action villain has. Players tend to be passive. (Metagame is important on bigger stakes)
On the flop, the aces aren't likely to still be the nuts (unless you flop quads or top set on a non-flushy, non straighty board), but they still are the vast majority of the time on the value side of the spectrum. You should be almost all the time betting or raising with aces on the flop, but unless you have a read on your opponent, I'd avoid re-raising aces on the flop.
Turn and river, if your opponent called your aggression pre flop, and on the flop, you should start thinking about showdown and exercising pot control. You don't want to be bluffed out of your aces, but they become no longer the monster they were on earlier streets.
SplitSuit channel on YouTube shows a wide variety of videos on tricky situations of playing aces.