Just grab a pair of sneakers and do your thing on them. Then just put them out in the net for all to see. You could end up getting commissions from it. Also hit up sneakers sites as well to get the word out that you're offering this service.
pigment liner pens....they're all sort of brands. I also use a pencil to lightly draw in the design onto the servise and a fixative spray to spray onto the finished surface. Hopefully, this was helpful.