Here's my promised step-by-step guide on how I sculpted my gladiator helmet.
2: To make the front half of the brim, I laid down a small roll of gs across the top of the mask.
3: First I blended the top half of the newly laid roll into the crown of the helmet ...
4: ... Then, using my fingers (wetted with a bit of water), I gently pinched the middle and bottom half of the roll into the brim's shape, while trying to keep it even around the front. Note- You do NOT need to actually "pull" the gs into the brim shape; the act of pinching it will provide enough "pull" to get the shape you need.
At this point, you can keep the brim level around the front, or you can pull down the sides a bit for a curved or other-shaped helmet.
5: Once the front half of the brim has cured, do the same with the back half. Lay down a roll of gs ...
6: ... Blend it into the top of the helmet ...
7: ... Then pinch it into a brim shape, making necessary adjustments here and there to keep the brim even all the way around.
8: I cut the crest out of a piece of cured gs and glued it to the helmet (dry-fit it first). If you have a gap where the helmet and the crest meet, you can use a touch of gs to fill it in.
This should be all the helmet you need, but you can go further, adding a horse hair crest (I'll add one on this helmet once I've put the helmet on a body), or some engraving around the helmet. There's a couple ways you might try the engraving (that I have yet to try); You can lay a thin layer of gs over the areas to be engraved and then either use the press-mold technique or grab a need;e and actually draw whatever images or designs you want on your helmet.