I make lots of alts. Basically I often get names I want to or on first, possibly second, attempt. As others have said, try some imagination.
What names not to pick:
Your favorite anime character. Those are already picked.
Your favorite movie character. Those are already picked.
Memes. Those are usually already picked.
Too obvious clever jokes. Those are already picked.
ect.
What usually works. Think of a fantasy character name. One that you came up by yourself (this is the important part). Doesnt go on the first try? Alter or add a few letters while still keeping it desirable.
You want some word that means something? Those are likely picked. If you still want, then think of a clever way to preserve the meaning while altering it slightly the same way as in my above suggestion. Add a letter. Alter a letter. Do not use ä or á, ect. Those are likely picked and look bad (in my opinion).
TLDR:
Anything obvious. Those are already picked.
Pick something you thought yourself.