Making c-bet by value is simpler than by bluffing
. Overall, every time you make a good hand - for example, a top pair or better - you should go ahead and do the c-bet. The main reason for this is that when you have a strong hand, it is crucial to build the pot as much as you can to get the most value.
Online poker professionals advise you to c-bet about 65% to 70% of the flops and the reason for this is that these bluffs have a high success rate. When raising preflop you are representing that you have a hand with high cards - Aces, Kings and Checkers especially - so flops that have one of these cards are perfect for bluffing.