Again different for everybody.
First follow me everyday and check how many games im winning and losing. After i lose several games, would be the best time to hop on board and actually bet.
If your talking about how much to invest, well this is different for everyone. If your willing to risk 500$ that you can afford to lose, then dont just place it on 1 game. You want to make sure you can bet on 10 games or more with the bankroll you start with incase we go on a cold spree. In which case you would start by betting 50$ per game or in some case a little more when we take a favorite. Do it for a month, provided that bank roll last. Obviously we are trying to make this work and it has been. From there you can be the judge of what you want to invest.
If your looking for a good place to place your bets then join at www.leadingsportsbook.com and always check in reduced for better lines then every site out there 99.9% of the time. Promo code ls35 will give you a 35% bonus but if your new to betting site then read about rollover. If you take the bonus then there is a roll over policy at every single site. The more they give you the more rollover they ask. If you have other questions please ask because i wasnt sure which part of how to start you were asking. And if you tell me what exactly you want to know then i can much more elaborate.