I like the Metroid Prime 2 HUD. Ammo and beams along the right. Health across the top. Map on the top left and visors on the bottom left and then I would adjust the options so it seems like you are viewing it through the actual helmet to up the immersion rather than weaken it.
If you don't have a suit, a minimalist approach works like the HL HUD
If you don't have a suit, a minimalist approach works like the HL HUD