I am going to give you the perfect formula for drawing with a pencil on metal buy you self a 4B or softer led pencil in a altoid tin can melt bees wax, regular wax white one preferred so it could show clear bees wax is brown you could buy candles the chip like I doo buy 1 chap stick know is the time you ask for what well the chap stick make it oily and it helps it when drawing on the metal you melt the wax and chap stick let it cool and re heat it so it would have a good mixture grab a practice plate and go ad it you could erase re draw just grab a Q-tip for erasing when you satisfied with your drawing grab the scribe and go over it
for drawing I would buy a sketch book it could be a small book size so you could take it with you everywhere you go and go at it everything you want to learn to do practice it there and watch your progress