Here's a simple little system I follow on Saturdays, just for fun really. If I go to the pub on a Saturday I still like to have some small interest bets during the day, and this one does throw up some nice winners. I don't have results to back this claim up, but I'd reckon this would make a POT by chasing best available price (plenty of options on a Sat).

1/ Sat Metro only
2/ Only consider horses with 1 start for 1 win
3/ Last start was at a non-metro venue
4/ Is not being ridden by a claiming apprentice

Seems fairly logical to me. Horse wins on debut at the provincials, and trainer then takes it straight to town on a Saturday. If the trainer is competent, these horses are good enough to win. Also I consider the use of an apprentice as a negative, as usually the horse is on the limit anyway, so no need to claim.