Brainstorming can only be used to a limited extent for the idea creation in logo design. This method qualifies especially if multiple persons use it.

If you are alone on your search for an idea, the method is not ideal, but it can nevertheless lead to very good ideas.

First of all, the problem definition is to be properly captured and noted down. Then, set a time limit - usually, 15-20 minutes will be sufficient.

Within this timeframe, note down every idea that comes to your mind. You don't need to think about the implementation or realizability of these ideas. Just jot them down.

When the time is up, start to sort the written-down ideas and approaches and remove unrealizable ideas.

This way, you'll receive a list of ideas that you might have discarded before. They may have seemed unrealizable before, but might be somehow realizable after all. In a nutshell: Just look for topically fitting ideas when you're brainstorming, and think about realizability afterwards.