As a general rule you should bet on sports that you know well.
It is important however to distinguish between individual sports and team sports.
With individual sports such as tennis, badminton and snooker, it is very easy for bookmakers to assess how well a certain player is performing at a given time. The odds that will be offered in this case will be a realistic reflection of the chances of winning and losing.
In team sports, there will be multiple factors at play. It could be that some players have been suspended or injured. If these are important players this can greatly influence the performance of the team. It is also important to take into account whether the team is playing at home or away. The odds offered by the bookmakers will not reflect the reality as closely and this could offer an opportunity for success.
In some sports a draw offers a separate possibility (e.g. football, ice hockey). The advantage is that the odds for a win or a loss are higher in such games, but given that there is also a third possibility in addition to winning or losing, your chances of winning also decline.