Originally Posted by steveiam
Generally a c-bet is a continuation bet which would be about equal to your original bet.
By definition a c-bet is always a continuation bet since the "c-" is short for continuation.
And it's size should be based on pot size, board texture, effective stack sizes, number of opponents, and reads on opponents. If you raise to 3bbs and are called by someone behind, then your pot is 3 + 3 + blinds of 1 + .5 = 7.5bbs. If you bet your original raise of 3 bbs, that's less than half pot and you're giving pretty good odds for someone to call with pretty much anything, especially if effective stacks are deep, and even more so if you have more than one caller (though generally you should be c-betting less often with more callers, again depending on hand strength, board texture, reads).
Raising and c-betting smaller is more appropriate in tournament situations because the effective stack sizes are smaller, but, as pointed out already, this is a cash game thread.