I am cis, but my given name was very aged for my generation and grandmotherly which made me self-conscious as a kid.
When I decided to ditch my name, first I tried using my middle name, but that starts with a different letter and it turns out my brain tunes that out entirely if someone that I wasn't already listening to calls it out. I had to already be engaged in conversation with someone to respond to it, which doesn't work great if someone across the room calls out your name to try to show you something cool. My parents never did the full name scolding so I literally almost never have heard my middle name spoken aloud. My dad even thought I had my deceased sister's middle name the last time I can remember middle names coming up in discussion.
I gave up on the name change for a couple of years, but in high school I decided to give something else a shot. I started using my first initial, but spelled phonetically, for example: K spelled as Kay or L as Elle. That was the solution I needed. If someone shouts it from across the room, my brain alerts just like with my full first name. It's simple, but it works. I've stuck with it for 23 years now.
I highly recommend picking something that has a starting sound similar to your current name so your subconscious brain will still pick up on it, otherwise your friends and family will be shouting your new name over and over to get your attention while you are completely oblivious. My kid is trans and I am going through this now from the opposite end of calling the new name out repeatedly with no response because he also picked a name with no similarity to his given name.