This may be old hat to some of you but I still don't know how to do it yet.
Last night I limped in on the button with something like QJ suited and flopped the nuts (8 9 T rainbow) and had 2 players in front of me bet. I just called the flop bet and the turn bet so as to keep them both in all the way to the river if possible. When we got to the river they both checked so I bet about 3/4 the size of the pot hoping they would think that I was trying to steal the pot. The both folded. Obviously either they had absolutely nothing or I bet too much and scared them off. Just how much of the pot should I have bet to at least get them to call it? Is there a rule of thumb for this situation?

I agree with Alex. Don't slowplay a straight. Bet it. Especially at low limits, people love to call on those boards because they figure they can make a straight themselves if the right cards come. Make them pay to draw.

My guess is that they were both drawing. Maybe one guy had say bottom pair and a straight draw. The draws didn't get there so they folded. They might well have called more on the flop or turn, though!

In general (IMHO) you can never induce someone else to call. Only their cards will make them call. If they have junk, they're not calling. If they had had a set or two pair, they would have at least called your river bet.

Thanks Alex
No, I don't have poker tracker yet but am planning on getting it sometime in the next month or two.
So basically what you're telling me is that I should have raised their 3x BB flop bet then? As it wordked out the initial bettor bet 3x, that was called by the guy in mid position, and I called as well to make it 9x for the round. The same for the turn bet round. But you are telling me that I should have raised the flop bet and risked not getting their turn bet money into the pot in exchange for finding out if they were willing to risk it all with their set? Is this correct? Or did I misunderstand you?

on a rainbow board, i like the flop call in position. it's a bit greedy, but you can afford to give a free card. fwiw, i think a flop raise is also fine, too.

but you absolutely must raise the turn...to charge a scared two pair or set, to wax a sucker straight, but mostly to build the pot. in nl, you must give yourself an opportunity to win big pots w/ the nuts, i mean, it's why we play poker, right? next time, drop the hammer, and if they fold no big deal, you probably wouldn't have gotten anything out of them anyway.

you have to bet the flop. first of all, even the nut straight is a vulnerable hand. you dont want people outdrawing you for free. second, the best way to extract more money from them is to build the pot as early as possible. this means betting/raising the flop. not huge...maybe not even pot-sized. but something. bad players with mediocre hands are more likely to call on the flop because of their small chances of improving their hand. and when the pot is larger on the flop and turn...its harder for them to get away from paying off your value bet at the river.

and yeah, they might fold to a flop raise. but if that's the case....you weren't going to extract a ton from this particular hand anyway.

jon