I have beaten the bookmaker.
I went to Chepstow races about 10 years ago and used a quite complex betting formula I'd devised myself. Bet on horses with claret and blue colours, if there are none, bet on horses with a chevron shirt that looks like a large V on the jockey. If there is no claret n blue and no chevron, don't bet. Nobody was more surprised than me when I finished the day about £40 up.
Two years later, back at Chepstow, same system and I finished the day £5 up
I've never bet before or since, I'm staying in profit.
oh, one more tip: bingo halls, where somebody has been playing a machine for a while and they think its due a pay out but they need a wizz or a bacon roll they put a laminated card on the machine reserving it.
Those are the machines to play.