No one can post all the great tips in a single post, however the best thing you can do is research and studying.
Study different things from other bettors, frequent betting forums, articles, newsgroups, youtube, twitter, etc etc. Study the sport or thing you are betting on. If you are betting on Basketball then watch as many games as you can, read as many articles as you can, hang around as many fans and people on the inside as you can. etc etc
Do all this and while doing it EXPECT TO LOSE, do it for fun if you must. You do all of that, eventually some day years down the road you may be able to make some decent money at betting. The odds are slim to none though, and even the greatest usually go broke at some point if they don't stop and walk away.