We don't use minis, but I do the same with artwork found around the internet. When I have a rough idea for a character, I often check Google image search, DeviantArt, etc. for art that would fit my idea and then build the rest of the character (appearance, weapons, and armor) based on that.
During the Next playtest I google imaged for a female barbarian and found one with the most haunted eyes. She was BROKEN. A whole tragic backstory came from that picture.
I'm a visual person, I often get inspired by these. I often hunt for pictures for NPCs when DMing because it will give me quirks and insights into running them.