Starting up my Amazon business

Hello everyone,

I’m looking to start my own Amazon business through FBA and I have about 5 grand to start it up. I’ve done my own research on how it all works, the fees, and the processes. I understand many people struggle with finding a niche where they are actually able to profit on. What process does everyone recommend to do to find my product? Is promoting that product valuable? After how long of limited sales do you begin to try another product?