Wait until a shooter rolls a 4 or 10. Then LAY $50 (or whatever you wish) against the opposite one. That is, if a 4 is rolled, then lay the 10, and vice versa. If the point is made by the shooter, take off your bet and wait for his next come-out... waiting for a 4 or 10 and then repeat the process. Of course, you win when a person 7-outs (unless he rolls your point first).
A variation of this (which does not bet anywhere near as often) is to wait until the point is 4 or 10 (as opposed to just rolling a 4 or 10, as above), and then proceed as stated.