Hey tryhardnoob,
C-betting half pot in 3-bet pots is ok. The ranges are usually much tighter here so there are no SCs or some strange hands that can suck out on you and people will give you more credit even if you c-bet some less.
As for regular pots, I think the best thing to do is to do the same bet sizing for value and as bluffs. You can deviate from this until you play high limits where players are very attentive, but the problem is if you bet too little fish will give you less credit, because according to their thinking big bet = strong hand. Anyway, in general just adjust your betsizing for the max EV depending on what your intention is and what bet size will fulfil your intention best, because even on mid stakes very few players give attention to your betsizing.
Best regards,
burek2000