I think that art is important to set the tone of a game, one of the reasons I struggle with Pathfinder is the ridicules art. Every time I see the barbarian in the main book with a sword made of 300lbs of iron I laugh a little. Conversely the classic black and white line art of 1E and 2E really hits the spot for me. I also think 5E did a great job of presenting more realistic art after the excesses of 3e and 4e.
In my original draft I used art pilfered from the B/X books and adventures of that era. I needed art as a place holder and to let my original play-testers know the style of play I was emulating. Obviously I have the financial sense to know that paying a competent artist to illustrate my vanity RPG is an unwise decision, but I also know a consistent art style is hard to achieve with public domain art.
I have limited artistic talent so I have gone the simple route of creating my own art using black and white silhouettes. This is time consuming as I use public domain pieces and slowly turn them into silhouettes in a often slow process. This is my latest piece, I am not entirely happy with the flail, and may change it to a mace, hammer, or sword.
My intention is this is not a werewolf, but a primal wolf creature, probably the terrible offspring of a titan and a she-wolf. I like the size of the wolf creature and the implied resolve of the crusading cleric bent on ridding the earth of this primal menace.