Just an example. I do this all the time and it works at least 75% of the time.

$2/$4 NL 6 max

I open raise to $14 with [7h]. The SB calls and we're heads up.

Pot $32. Effective stacks $350. Flop [Td][3s]. he checks, I bet $20 and he calls.

Pot $72. Turn . He leads $8. I raise to $58 and he folds.

I dont have any set percentage. I just make the raise to a big enough amount that it looks like I going to be shoveling a huge amount of money in on the river. Remember though that I would make that same raise with a set or 2 pair on this board.

I would make the raise alot more often if there was a flush draw on the board. Im not sure this is the best board to make the move, but his bet was SOOOOO friggin weak, i though it would work.