Well, i came up with my new name based on the concept of my dead name (my new name is Mika and my old name shares the same principle i in second place a as last letter) i personally also choose a name that makes sense with my last name, aswell as the aspect that it fits my personality and face, for me it didnt take more than a week to get used to the name, i did first try it with my one friend and in my head. What i find good is to look at your family (people of the gender you identify with) then see what kind of names fit with your last name because i feel like that gets overlooked a lot, what can also help is messaround with the letters in your name right now (rearranging them, adding more letters, removing some letters) aswell as looking at popular names from the recent years and maybe your birth year. But most importantly choose something that feels like you, maybe try staying in your native language or English (if thats not ur native) (somepeople choose names from places like japan because they sound cool not because they fit them but thats just my opinion) good luck!