Can you use maybe to start a sentence?

Yes, you can use "maybe" to start a sentence. It's perfectly grammatically correct.

For example:

* Maybe we should go for a walk later.

* Maybe you could help me with this project.

* Maybe I'll see you tomorrow.

However, starting a sentence with "maybe" can sometimes sound a bit informal. If you're writing something formal, you might want to consider other ways to start your sentence.