A couple of rules worth considering to select a horse could include:

1) A fairly high Win S/R. Sort of proves that the horse has ability, is placed fairly well and importantly that trainer likes to win with it.

2) A win this time in. Wait 'til the horse has shown a return to form.

3) A minimum number of wins and runs. No use backing a horse that has 2 from 2 is it? It needs some history.

Does anyone else follow S/R?