There's no one answer to this question since it can vary depending on what type of essay you're writing and what your goals are for the brainstorming session. However, here are a few general tips to keep in mind that should help you get the most out of your brainstorming:
-Start by clarifying what the essay prompt is asking. This will help you focus your brainstorming and come up with ideas that are relevant to the essay question.
-Brainstorm with a group of friends or classmates. Having other people to bounce ideas off of can help you come up with ideas you wouldn't have thought of on your own.
-Don't worry about coming up with perfect ideas. The goal of brainstorming is to generate as many ideas as possible, so don't self-edit too much. Just write down whatever comes to mind, no matter how crazy or out-there it might seem.
-After you've brainstormed for a while, take a break and come back to your list of ideas later. This will help you look at your ideas with fresh eyes and might give you some new insights into which ones are the strongest.