Do we C-bet dry board or let villain see a card when we hit top pair ?

[DonkeyBets]

One of the biggest things I am confused about is when to c-bet or bet after the flop in a hand, We bet to get value from worse hands or to bluff villain off better, but lets say we have T9s, we are on BU and raise to 6bb, sb calls and the board comes 2d,6c,Th, We most likely have the best hand against a villain who is looser than average but we dont know if we can bet for value because they might not have much to call , but we dont want a high card to come on the turn and let him take the pot away. So how do we know when to bet and when not too if we don't know that theyve hit or not,, we dont want to keep letting villains see free cards and have chance to catch better pairs but we also want to keep weaker hands in the pot and call