I place the big 8 ball on a piece of chalk in the center of the table. The 1 ball is hanging in the near side pocket and the 3 ball is half way between the 8 ball and the other side pocket.

I place the cue ball about a diamond out from the 1 ball. You have to aim pretty straight here, but any little push should send the 8 ball rolling. The cue ball needs to carom straight back and you need to get out of the way in time too. There shouldn't be any problems with the 8 ball or 3 ball unless you're not lined up straight.