Argyle King
Legend
A variation of this is to take your three initials, and then plug in as much of each name to "bridge the gap" to make a decent sounding name.
My initials are JMR, but "Jmr" is unpronounceable. So I slap in the second letter of my first name ("o"), and the second letter of my middle name ("a"), and get "Jomar" - that could work.
If one of your initials is a vowel, you might not need anything else to bridge the gap. I have a sister whose initials were "JAR," but since she wouldn't want that for her character's name, she could try adding some letters from her middle name. Unfortunately, her middle name is "Ann," so "Janr" or "Jannr" isn't much of an improvement. So, going with more from the first name ("Julie"), and we can get "Juar" or even "Jular." Add on some from her last name, and we can get "Julari" or "Jularich."
It's not a perfect system, but it can be useful.
Johnathan
My initials are JD; bridging the gap gives me "Jod." Jodi if I use the first letter of my last name as well.
JSD if I use my middle name...
Josd...
Josdi (maybe)
Joscdi... Joscodi... I think I like Joscodi as a surname or possibly a name for a liquor.