betting the flop or the turn?

In limit games people will always call even with weak hands. Let's say I have a modest two-pair on the flop and I bet, I've found that I would have to then bet the turn and the river in an attempt to get the other players to muck.

The problem is, if I bet the flop, I'm basically forced to bet the turn and the river otherwise the other players will bet because they sense my hand has weakened and they start getting aggressive.

My concern is if I bet all the way to the river, I'm basically investing 6 big blinds which in a game like, say, 4-8 kill, translates to $24 invested into a marginal hand.

Would it have been better to check the flop, bet the turn and river? Doing would mean I invest 5 big blinds instead of 6.

2pair is a REALLY strong hand in most situations especially if your opponent is just calling all the way. Bet, bet, bet in most cases.

Agree with hillbilly. You want them to call you down when you are holding such a strong hand.
Don't think in terms of money... you have to let go and think of them just as chips. In terms of # of big blinds. If $24 is too much, then you have to drop down in limits... I know impossible to do live, but you don't want to play with scared money.

what is a modest 2-pair? you act like you're bluffing.

Just bet it through you are probably ahead on the flop and betting will get few fools to fold but the ppl with draws or a pair will call you down if they no how to play limit and understand odds. If draws don't hit probably folding your river bet unless they have A high and feel like being a hero (more money for u) and if players with a pair sticks around believe it or not they are probably priced in to call you since it is a limit game. In low stake limit games if you hit the flop really good (2pair, set, or better) u bet it all the way unless craziness comes out then u probably just check/call (your priced in more times than u realize). If you hit board low, top pair or less just call ppl down hope to get better or maybe already be good enough. PPl mistake odds in limit games by trying to play NL style

let me see
if you have top pair top kiker you should bet if there is a draw in postion if you out of postion i would check because the first bet will not make the draw fold all what you will do is just put some cash in the bot that the guy that draw will win eventualy if the draw came so i check call depened on the size of the bet

if you have top set you should check if you in postion or out of postion if there is draw but if you in potion and the guy before you bet you ofcource know what you do if there is a big draw i bet out of postion or in postion and i try to think if he is drawing or he have top pair and it is good idea not to lit him get to the river cheaply becouse you will have to pay him if he have the nuts either way that depend on the player also