Here's my contribution, eliminate any horse that has not won in the conditions. Unfortunately this means that you can't decide on whether you bet or not until not long before the race but all the statistics i've looked at in my endeavors to find a profitable system show that if a horse hasn't ran or won in the conditions previously theres a good chance it wont win this time around. Obviously horses have to win in conditions at some stage to meet this rule but as I generally do my ratings on quality races with horses that have had at least 3-4 starts it seems to work quite well.