You cbet what you would bet if you had hit whatever it is you are trying to represent.
So, if you hold AQo and raised preflop and the flop is K rag rag, you bet as though you held AK. If you held AK and the flop is Q rag rag, you bet as if you held AQ.
If the flop is triple rag and you choose to cbet, bet as though you hold a premium pp (JJ+).
Any variation in your cbetting vs your regular protection / value betting can and will be picked up on then exploited by observant players. Instead you should vary your bets to what you would bet on that flop. EG, flop is again K 7 2 rainbow and you hold AQo. You can cbet half pot because its a dry flop. Change that flop to K
7
8
- now you must cbet at least 2/3 to full pot as you are representing TPTK protecting vs a flush / str draw.