How should I Decide on what design pattern to use for my code?

I need to choose two Design patterns and implement them in my code for a college assignment, I don't have any superclasses, only 5 regular classes and a tester. I'm not really sure what to do. The assignment says that we have to choose two design patterns and implement them in our code. We have just done Serialization and Deserialization in the previous assignment so this is a continuation on from that. Would anyone have any advice on how I should go about this. We can choose any of the 23 available design patterns to improve our code.

Thank You