Also not an artist by trade, or a musician, sound designer, programmer or writer, that's part of the fun.
I normally make my own assets. Over the last year my main focus has been improving the music I make for my games, and I think it has improved a lot from where I was.
Making your own assets increases the work load for a jam, but it is quite rewarding knowing that your game is unique, plus you don't have to worry about licenses or credit for your own work.
The new art style I'm using this time is a simpler hand drawn style. It looks ok for a jam game and I have got most of the game working as I intended, I only have to get a few menus and Sound Effects done, then I'll probably even have time to add a little polish and balancing to the game.
To be honest it has come together a lot quicker than I thought it would as I didn't start till Tuesday.