The major mistake people make when betting on sports is not caring about the odds.
You need to bet
early and be able to predict the odds you are betting on will
drop soon or later.
Your bet is a good bet only if you manage to get better odds when you placed the bet, compared to closing odds (odds of your selection at the start of the event).
Example: Nadal vs Federer
Odds: 1.95 / 1.95. You bet on Federer @ 1.95
Closing odds: Nadal 2.00 vs Federer 1.86
Your bet is a good bet, even if Federer loses, because you were able to get the value on Federer.
You may lose your bet but you should be able to get a profit over the long term. You can read this article about it >
https://easysportbet.co.uk/why-are-closing-odds-more-accurate-than-opening-odds/It is not an easy exercise, it takes a lot of practice and experience, and the most important is to stick to sports you know best. Avoid tailing other people, and you will give yourself the best chance to win over the long term.