Check out EFF cover your tracks: https://coveryourtracks.eff.org/
The results are very interesting. For me, the most unique thing about my browser was that I had two system languages, and so the accept-language header was very unique.
I now use vanadium (graphene OS), which simply sends made up values for a lot of headers, and so makes fingerprinting harder.
In general, you should try to be as "normal" as possible, use standard settings for everything, just accept English, etc..