Not knowing the outcome, in sports, is at least half of the fun. Yet, trying to predict the outcome is part of that fun; even before the event begins, armed with statistics and knowledge of the past and a cunning shrewdness to try and apply it to the future, or when the event is on its course, when we observe developing trends and, wishfully or not, we project them, we elongate them with our imagination until the moment the encounter is supposed to end, so that we come up with a parallel recreation that contributes as much as the immediate senses to pump up our adrenaline level.
When it comes to the method, there are several keys to success in sports betting, the chief among them being, probably, the 'Kelly Criterion' of betting proportionally to our advantage, that is, putting our money where our knowledge is. That being so, if we have spent our childhood gathering basketball statistics we shall have a more than average result betting there, and the same goes for football, baseball, F1 races, etc. If that is not the case, then betting where the outcome options are the most reduced is recommended: after all, if we try to randomly guess the simple outcome (i.e., who wins) of a tennis match we have a 50% chance of being proved correct !
Once we have decided where to bet there are other factors that we shall as well use in our favor, like keeping a complete record of our bets, that is, how much we spent, how much we won, that on which the bet was based on, etc, because this will allow us to be rational rather than emotional in our future bets and, on top of that, not letting just our last result (be it a win or a loss) influence too much our future bets.
And one last thing: according to Prof. Nassim Taleb is far more secure (let alone much more entertaining) to bet 80% on quite predictable outcomes and 20% on the riskiest ones we can find (providing that they will render us more benefits if we get them right), than all our money in mildly risky bets.