I will move this to the more appropriate topic for you, Vernsim. You will get a lot more replies there.
For me, I started out with chalk and kept using it till I figured them out. Then, when I wanted more detail work, I went to the Prisma pencils and kept practicing with them. Now I am on the acrylic kick and will be practicing a lot with those.
Best advice I can give is once you create your sketch, scan it and print out several copies to practice on. Once you get the hang of the medium you are using, use it on your original sketch, or just leave it be on a sketch copy.
Good luck!