A system that can be profitable using the exchanges is to predict the price movements of certain horses based on media coverage. A heavily tipped horse in the red top newspapers will often lead to a weight of “mug punter” money being laid down at the high street bookies.
This will be reflected by the big chains shortening the odds, and in many cases hedging the liability on the exchanges. This in turn will push down the exchange prices. So in the evening you can get online copies or the first editions of tomorrows papers and look for suitable candidates.
You want races with over 8 horses, and for at least 5+ tipsters choosing the same horse, and no other horse having more than 2. Once you have your selections back them either at EP at the bookmakers or at the current rate at Betfair. Then set up a lay at 15% shorter odds for a 10% increase in your stakes. And then go to bed. Early on the following morning with any luck the money will start to be put down and your bets will have been matched locking in a return.