Here's my process without endorsements of any kind. After the title I think of what characters I need, or need to bring back from a previous part of an arc...and think of an appropriate name. Then I try to picture them in my head as to how i believe they look like. Then next, and thanks to another author friend, I do web searches and try to find an avatar which most closely resembles them. Hint...it would be so much easier if you could do a mind picture dump; because I've very rarely found an exact match. Also when doing picture searches, if I find an image which I think would fit at some point, I put it in a folder called "character barn". if I need a new character that's usually where I look first.