I think the best advice for when you start drawing with no prior experience is to just draw what you want and to not focus too too hard on bettering a skill you don't have. Get used to drawing first, put in your hours, have fun, and then you can worry about getting better. If you spend the first thousand hours of drawing are studies and looking at references, you won't have as much fun doing so as you would otherwise. Get a sketchbook or two. Try out different mediums from watercolor, pastels, acrylics, colored pencils, to ink pens so that you can find what you enjoy using the mist. Having a strong foundation for your art work is great, but prisons also have strong foundations. And prison isn't fun. Make sure when you make consider a strong foundation, that you can enjoy yourself while laying it.