Pretty much as a rule of thumb your 20 yd pin will shoot about 2 inches high at 10 yrds. So go ahead and get it pretty close from there and make sure you have made all your windage adjustments so you are definately center aligned. After you get it in pretty close to the 2 inch rule, go ahead and move back to 20 and take a shot. Dependent on how fast your bow shoots will usually be how close you are to being on at that point at 20. So from there just make minor adjustments until you are getting a good shot group at twenty, probably from the sounds of it around a softball size or so. Now your 30 yd pin should be more or less the same distance lower as your 20 is from your 10. Not always right on but pretty close. So set it up and then repeat just as you did for the 20 but this time your shot group dependent on your level of shooting will probably be just a little bit bigger than your 20 yard pin.

By the way my suggestion is to have a 20, 30, 40 pin set up because like i said you will already be about 2 inches high and that aint bad and easliy eyeballed from that distance.