No problem. If you can give the finger to someone, you can do what I do.
I use number 2s on letter size copy paper, nothing special. I use a combination of useing the side of the graphite/lead like you do and a lot of lines drawn in like I was shadeing useing just lines. I try to draw the lines to fit the shape of the section of the drawing. Move the pencil out of the way, extend your finger, index or middle and rub the sucker in. Your finger will smear the lines together forming a uniform gray. The darker the pencil mark, the darker the shade of gray. Now your finger will get pretty black so you might want to use some kleenex to rub with. Go over darker areas and smear again. Use a good eraser and useing the sharpest edge of it, use it like a, well, a eraser. rub it over the areas that you want to highlight, sometimes a little, sometimes a lot. Brush off the bits of eraser, then rub it again. That will take out the sharpe edge of the erased area and blend it in.
The hard part is to get it to look like a picture when you're done. I'll add a drawing that is incomplete showing stages of what I mean.
This one has just a few little things that I wanted to add to see how they look. I can't to head patterns worth a darn.
I tried for a chest design with this head.
Another Bio-helmet. I keep trying to find one that I like. If this one was ever sculpted, I thought about fixing it so that a light stick could be inserted into the laser sighting unit for an erie glow.
I started this one based off of the AVP Elder. It didn't turn out.