Well I'm sure that it's going to be a little bit difficult to draw the two, but basically they follow just one pattern.
Things you'll need:
With that, we proceed to the next step.
Sorry, I have no images to post, since, I have no access to the scanner.
Search google on how to draw a male body. Though what we will need is a young kid's body. Just shrink the size, then remove the muscles.
After that, you can put some other details, like the eyes and everything.
For the helmet (let's begin with that one), you just have to assume that it's covering 3/4 of his entire head. that's where your perspective comes in.
For the rest of the details I suggest going through the official artworks as referrence. Then use your perspective and proportion to draw it.