KTo on button, flop TP multiway

[dark_horse]

Here's a hand I played at a B&M 3/6 game today. The game was quite fishy, loose and semi-aggressive. I was on the button with KTo. I think there were about 5 limpers, so I limp on the button. The flop comes raggedy with a K (don't remember the exact cards, but they don't matter much here - I think it was rainbow), and it gets checked around to CO who bets. I have no read on him as he just sat down. After the hand, a solid, tight friend who was playing with me told me I should have just called down and never raise and let him bet all the way. Anyway, I raised on the flop, everyone folded but CO called. On the turn (again I don't remember any of the other cards, unfortunately) he checks to me, and I bet, he calls. River, he checks, I bet, he calls, I flip over my KTo, he flips over KJo and takes the pot. Now, had I simply called on the flop and he then checks the turn, should I bet? That's where my confusion begins, when I stop raising because I'm not sure where I'm at in the hand. I felt raising on the flop was correct because of all the players left in the hand. I had a vulnerable top pair medium kicker hand that I felt needed protection, and I did get everyone else to fold. But what if we were heads up on the flop? Do you just call this down? Hands like KT/QT/JT/QJ and even KJ/KQ can be tough to play when you've hit your top pair.