Trans guy here. There was no masc version of my deadname, and my parents didn't have a name picked out for if I'd been AMAB, so those routes were closed to me. I initially tried to pick something where I could keep my initials, but the only names I liked were already "in use" in my social and family circles, and it didn't feel right.

So I looked at the popularity of my deadname in my birth year, then started from that same rank on the boy name charts for the same year and worked my way out. I found a name of very similar popularity that I really liked, and met my other self-imposed criteria (nickname I liked, no nicknames that I hated, not easily misspelled or confused with a femme name). The benefit of looking at birth year popularity ranks is that I ended up with a name that doesn't sound "too old" or "too young" for me, which may or may not matter to other people.

My parents did something similar when they named us, so that we'd have names that were recognizable, but we wouldn't share our name with five other kids in our class. (My mom had a very popular name for her age group and she hated it.)

For my middle name I picked a name I always loved but that I didn't want for my first name, for practical reasons (easily misspelled, gender neutral, much more popular for younger kids than for my age group). In my area, nobody ever knows your middle name unless you go out of your way to tell them, so I let myself have more fun with it.

It's been close to a decade and I still love both of them. I "tried it on" with friends for a few months before starting legal paperwork, and I'm glad I did. Some other names I tried out didn't stick.