Information - Do Not Bet Without It
Information is the key.
In how many circumstances is that applicable? I'd guess quite a lot.
None more so than in gambling. Many people choose to bet almost at random; they may fancy the name of a horse or have a lucky lane at the dog track or just blindly guess a winner. Almost all of the time these people will lose out overall. To consistently win, you must have sufficient knowledge.
Take horse racing for example; by guessing a horse blindly without any insite you might get the occasional win but it is more than likely that you will pick a loser.
If, instead, you were to take a proper look at information available to you, it is possible to eliminate a good percentage of the horses in each race before you even start.
Try to focus on some of the following details: the form of the horse, the form of the jockey, the form of the trainer, the going, the distance, the weight a horse is carrying, the draw, the most recent run.
The same principles apply to all sports. Look at what your given and you will find you pick far more winners.
Practice these techniques and soon you will be able to weed out any risky or unlikely bets in an instant, leaving just a small selection of potential winners to pick from.
Decide if you think the bet is good value. For instance; if a horse has odds of 7/1, do you really think that this horse has got a better than 1 in 7 chance of winning? If you can make justified claims that this is the case then place the bet.
By judging what is and what is not a good vlaue bet you should be able to make a profit in the long run. Value bets are a good method to work to; they may tell you that an odds on favorite is not really that safe, or that an outsider has more of a hope than the bookmakers have given it credit for. Either way, you can make wiser decisions.