Donna was always going to be the most difficult character for me because out of all of them she has the least features. I started by doodling more images of her using photos, to try and work out which of her features were most important:
I then did these scribbles of her and the Doctor, to see what poses I could draw her in:
I then had a go at establishing some shapes and getting proportions right:
I think I'm alot closer to getting some shapes I like out of her. I just need to get her to fit in visually with the doctor!