Many people are trying for years to do that, and mostly are unsuccesful.The reason is poor knowledge about the events they are betting on, poor money management, greed and maybe the most important thing poor overall strategy. But with help and professional work, this can be accomplished on the long term.
A professional punter will never bet on an event that knows nothing about it but the league table.He will never "pick a winner" no matter what the odds are ! And this because you actually bet on odds not on a team, and that is why the odds are the most important thing in betting.
Staking is also vital.There are several resources on Internet about staking, and also there are several styles of staking, depending of the punter (Some use flat staking, some only maximum bets, etc) but most probably you should find the strategy that fits you the best, according to your hit rate.But never forget one thing: don`t bet more than you afford to lose.
The best successful strategy may be the "betting syndicate".Punters meet in places like private forums and share their bets.And usually each has an area (league, sport, etc) that he is following closely to gain an advantage over the bookmakers, and to find value in odds (This means he can actually estimate the chances for an outcome better than the oddscompiler did so he can see if an outcome is overpriced).It is vital that you follow all that punter`s bets, and also very important to bet on the same odd he did.If he`s a good tipster and makes profit, you will do too.
What`s the advantage of a syndicate ? Well, if each of it`s members gain let`s say a 10 % yield do a small calculation and see how much this means when there are 20-30 members on that betting team.
