First of all you have to choose a good betting agency. The web is full of shiny promotions and bonuses, but most often these offers are hard to be successfully done by a new backer.
The offer of sports is huge so it's better to focus on 2 or 3 sports that you know better and more focus on several championships that you can follow closely.
In this betting activity, like in everything else, the information decides who's the best so be sure that you are closely informed with accurate statistics, fresh information about players, teams, weather.
The experience is the big issue as well so you better start betting on small amounts at the start and raise your stakes after you get the whole picture.
Live bets are a special betting area as they require lots of experience and cold blood as the odds change very fast and you can easily lose big amounts of money.
All the betting agencies have the necessary experience and the psychological background to know how a common backer is betting so the only way to out beat them is to find your own method and own rules that you must respect 100% in order to have 1 cent plus at the end of the day.
One more important issue is to bet only as much as you can afford, because the line between fun and disaster is very thin. There are lots of people who ended selling their houses just to have money to bet, having a sure feeling for a certain result.
No matter what the odds are and who are the teams involved the result can't be 100% sure so be sure how much money you spend.
So good luck and be careful!