You just have to stick to legal, regulated online casino sites such as BetMGM, Caesars Palace Online Casino, FanDuel, Betway, bet365 and BetRivers. They offer great casino game ranges and they will pay out quickly and without any issues if you win.
Learn everything you can about the teams and the sport. Use Twitter to gain insight on lines and bone up on all the analysis you can. Be sure to understand your own stats, too: your winning percentage, units, and ROI. This bit might seem a little tedious, but time spent on research will help protect your bankroll.