Your first step is to determine which type of reaction is going to take place.
This takes a lot of practice. The more experience you gain the easier these types of questions will get.
The main types of reactions you should be familiar with include;
Synthesis (also sometimes called combination)
This video discusses the basics of how you determine what type of reaction will occur based on the information provided about reactants. Once you know what type of reaction will occur, applying a few simple rules will help you determine the products.
Hope this helps!