My armor was assembled based on the recollection of one of the Special Edition stormtroopers. He posted a sketch of how the screen used suits were put together on RPF. It was done from memory nearly 10 years after the fact so it may not be 100% accurate, but it works well regardless of its authenticity!
First off, I didn't bother with the hard hat liner. Too much effort, for not enough gain. Much like the original helmets, I just have a bit of foam in mine:
Next are the lenses. I'm a big fan of the stunt/background style flat green lenses, rather than the smoked grey bubble lenses that most kits include. Dark green welding face shields are really easy to work with, and provide a dark, camera-flash-resistant lens that can be cut easily with scissors. Mine is really a lens, vs. 2 separate lenses. I found it easier to attach that way. I hot glued it in the center and the far edges. Leaving the rest unsealed allows a bit more airflow, and reduces the risk of fogging.
My next antifog tip comes from the screen used helmets I've gotten to see. They've all been RotJ era, so this might not apply to ANH, but either way it works out well. Take a look at this photo from an exhibit:
See the 4 small holes under the eye? You don't see them from the front, but they really help with fog!
The entire torso is basically one big piece. The straps connecting the chest to the ab plate and the back to the kidney plate are elastic held on with velcro.
The butt and kidney plates are permanently connected via 2” white nylon webbing. I knew that they weren't going to be moving around, so I didn't need to worry about having room to stretch.
The shoulders are connected with white nylon webbing. The right side is permanently attached, both front and back. The left side is permanent on the back, and velcro on the front. The head hole in the armor would be too small for me to actually get my head into, were I to make them permanent.
The shoulder straps have snaps set into them to attach the upper arms. The snaps are covered by the ribbed ABS strips that go over the nylon.
There are velcro spots inside the ab plate to hold up the thighs.
On the outside of the armor there are a couple of squares of velcro to hold on the ABS shoulder straps. Once the armor is on, the shoulder straps are attached by someone else, since at that point you probably won't be able to reach your own shoulders!
If you are doing an ANH style suit, you'll want to change the buttons that come with the FX armor kit. They are larger than they should be - you can get smaller buttons at Tandy Leather. The buttons should also be grey and blue, not black.
I made by belt separate from the armor. If you're building an FX kit, you may want to replace the plastic belt strips with canvas or elastic. The fit will be better, it will be more movie accurate, and less likely to break.
I attached the drop boxes to the belt via elastic straps. They are glued on. If you use velcro, you'll lose them!
My biceps attach to the shoulders with a velcroed in elastic strap. This keeps the biceps from slipping around, and also keeps the shoulder bells in place. The strap at the top of the shoulder has the other half of the snap to connect to the torso.
I glued in the elastic for the hand plates. Your kit probably says velcro, but if you do that, you will most likely lose one at some point.
The knee plate and energy cells are riveted into place.
I heated up the energy cells with a heat gun to bend it to shape. If you just force it, there will be constant pressure on the rivets, and one might pop.