You can purchase tactics before each match to try and increase the likelihood of certain match events happening.
A description of what each Tactic may do can be found underneath the main tactic image. For example some will increase the odds of receiving goal scoring opportunities, some will increase the odds of experiencing a better quality of shot at closer range and so on.
Please note: The game randomly 'rolls' before each match to determine the number of default opportunities given. The lowest number you can receive is 0 but the highest number depends on which team you are up against. If they are a top-flight team their defense will be strong so you'll naturally you may have less opportunities.
Please bear this in mind if it doesn't seem that you've had the opportunities you were expecting - it's very likely the tactics have given you chances when you might otherwise have had none.