Here's a few of my gambling tips:

Never bet on low scoring sports that can result in a draw (eg. ice hockey, soccer, etc), as it's too easy for a favourite to lose if the underdog has one or two lucky shots.

Never bet against a home underdog.

Never place a bet without doing all your own research.

Before I finalize my bet, I ask myself if I have any doubts that the bet would win. If I'm not completely comfortable with the bet, then I don't place the bet. As a result, I usually only end up placing a few bets every day, but I manage to win about 95% of the time. The times I lose, it's usually the result of a big upset. The returns on the winning bets are small (1.05 to 1.3 usually), but consistent winning returns does mean profit.