I think you're not getting a lot of tips/comments because of the subject. It's relatively spherical, thus the different (& simplistic) lighting setups are harder to comment on/notice.
Use something with contours, much like a face would have. Say, a Halloween mask, a large toy that a sibling has, or just something close to a face. (I say close to a face because that seems to be what you're going for in your last few posts, portraits.) The many contours in a mask (face) will accentuate the shadows and make positioning more clear to you as you experiment.
As for these shots:
1) You lost detail in the chin strap hanging & the sticker (which is the most interesting part of the helmet). However, I like the way it's diffused so as not to appear as a glare on the helmet.
2) The fill light is too low, you're illuminating the inside of the helmet and not enough of the left side (sticker). Same lights, different angles, would make this shot better IMO.
Hope that helps, keep posting! I enjoy seeing others progress!