The best online betting sites include Bet365, William Hill, and 888sport, known for their reliability and diverse betting options. To increase your chances of winning, start with thorough research on teams or players, use free bets and bonuses, and manage your bankroll wisely. Avoid chasing losses and set realistic goals. Utilize odds comparison tools to find the best value bets. Stay updated with sports news and trends, and consider using betting strategies like arbitrage or matched betting. Remember, while betting can be profitable, it also carries risks, so bet responsibly.