Your choices and opinions all come from somewhere. When you want to talk about the reasons for your ideas, you can say that you've "based them on" something.
For example, when a teenager decides which university to go to, she might choose "based on" the school's reputation, the cost, which school her friends are going to, the school's website, etc.
Here are some other examples:
I based this recipe on a dish I had at a barbecue restaurant in Texas.
I don't see why they awarded it to this one. What did they base their decision on?
I base my opinion of a person on how they treat the people around them, not on how much money or education they have.