Continuation bet - how far?

Continuation bets.

When revueing my hands I find this is where a lot of my money goes.

Three situations, I find myself in A LOT.
How far do you take it. Assume you're at a LPP table.

1. Hero had AQs in CO. 2 limpers, Hero raises, 3 callers.
Flop. K,7,2r
3 checks, Hero bets, 3 callers.
Turn. T.
3 checks. Hero bets. 2 callers.
River. 4.
2 checks. Hero?

2. Hero has AK in UTG+1. Hero raises. CO calls. Blinds complete.
Flop. Q,7,2r.
BB bets. Hero raises. CO calls. SB folds. BB calls.
Turn.
BB checks. Hero?

3. Hero has TT in CO. MP1 limps.Folds.Hero raises. BB, MP1 call.
Flop. K,7,4r
2 checks. Hero bets. 2 calls.
Turn. J.
2 checks. Hero?

Continuation bets start to make me wretch when you're not catching cards. Especially when you're not catching cards and people keep looking you up because of it. Do you just keep donking away?

It's generally pretty easy when you hit your hand. These situations when you don't hit your hand happen often and seem to be where most of my money goes. Suggestions?