Unfortunately I read this thread and watched the videos after I did all my fiberglassing, so I did all mine through trial and error. But I see a lot of common questions and thought I'd do a little FAQ on my experience. I did it a little different, but for the most part, all the techniques are the same.
Q: Fiberglass cloth or mat?
A: Both work. I personally used cloth, it's much easier to work with and less messy, but I think the mat might be slightly stronger. I used cloth first, then tried mat, did about 3 pieces and threw it out, it was just too messy for me to work with. Someone also asked about type/thickness. I went to HomeDepot and they just had 1 type of each, so that's what I used.
Q: Do I use cloth/mat on the outside?
A: No, only use cloth on the inside, apply just resin on the outside. If you apply cloth/mat to the outside you'll lose that nice finish and detail. You'll see what I mean when doing the inside.
Q: How many layers?
A: I did 2. I wasn't sure myself but then did a 2nd layer on a piece and found it significantly strengthened the pieces as well as gives you more depth to work with when sanding. At the least, I would recommend 2 layers on most of the body parts since you run the risk of bumping into things, people knocking on it and didn't want to risk it breaking on me after putting so much time into it.
Note: The suit seems like it could get quite heavy, IMO more than 2 layers will give it more strength, but adds more weight. Up to you. Try an easy piece and do 3 layers, see what you think.
Q: How many drops of hardener/oz of resin?
A: The stuff I bought said 12-14 drops per ounce. To little and it won't cure well, too much and it'll cure too fast and become brittle. I used about 10-12. This seemed like it gave me about 8-10 min before the resin started to get gummy and not workable. I typically worked with 2oz at a time. This was about the right amount to use up most of the resin before it started to harden. On larger flat areas such as the thigh or chest, you could probably do 3-4oz since the application goes much faster than the smaller more detailed pieces. After 4-5 batches you get a good feel for how much you can do at a time.
Q: How to reach the hard-to-get parts?
A: Crackhead was right, use something like a pencil, scrap of wood, anything that can reach inside the areas. It also works good for pushing down the corners. Though any place you can reach with your fingers you're better off. You can do a better job felling the bubbles pressed out and smoothed than with a utensil.
Q: How to attach the visor?
A: I actually haven't come to this party, but here's my thoughts. Trim out the opening so it's nice and curved, taking out the geometric sides and corners, this will help form-fit the visor. I plan to put velcro strips on the back insides at the ends of the helmet, then put corresponding velcro on the visor. If you push the visor out as much as you can, then fasten it on the velcro it should make a nice tight fit. Personally I don't think you should use glue/filler around it, it might look "icky." I also thought of taking some thin weather stripping and lining the edge, this could help form-fit it better. Just thought though, haven't tried it.
Note: Abrant3 has a great vid on youtube about fitting the visor, search for him.
Here's some other tips I have:
Applying the cloth: I never tried the dipping method, so here's what I did. I first painted a thin layer on the area I'm applying the cloth. I then laid the cloth down and rubbed it down with my fingers getting all the air pockets out and working the under coat of rosin in. I think applied another thin coat on the top, also working the resin in with my fingers making sure to cover and saturate all the areas.
Cutting the cloth: Rather than using many small pieces, I would semi-custom cut out pieces to fit the areas I was working with. I think this method goes a little faster since you're not working with more smaller pieces. However, on more detailed smaller areas like the helmet I used lots of smaller ones. They're easier to work with in more detailed areas and helps eliminate air pockets.
Gloves: I used disposable latex gloves, a pair for each application. They were about $8 for 100 so you get 50 applications per box. I did smaller areas at a time so I think I went through 2 boxes.
Resin: I'd recommend buying a gallon at a time. The smaller 32oz cans cost about $10-$15, where a gallon is only $30 for 4 times the amount. I used about 2.5 gallons on the entire suit, though I think I was a bit more wasteful than most.
Hardener: Buy extra tubes, the amount they give you is not enough to last the entire jug. Again, I used 10-12 drops/oz, so maybe using only 8 as crackhead did will be enough.
Mixing: I bought small plastic mixing cups for about $.80 each, I think they work nicer than the lid though you can't really use the dipping method as well. I also bought 6 so I could do multiple batches back to back on various parts. If you're just working on 1 piece at a time then no need, but I fiberglassed the whole suit at once, so this moved things along VERY fast. 1 layer on the entire suit took just over a week. That was 1 coat/weeknight and 2-3/day on the weekends. 6 batches would take me about 2.5 hours. That's with prepping the pieces, cutting the cloth, application and cleanup. I'd then let them cure for 2 hours before doing another coat on the same piece, so if you're ambitious you could do 2/night on the weeknights.
Brushes: I started with 2" bristle brushes and Acetone to clean up. I ended up spending a lot of $ on Acetone and the brushes got about 5-6 uses before I couldn't clean them anymore. In the end I bought a box of 288 foam brushes from HomeDepot for $65. I only used about half the box, but in the long run it was far less expensive than cleaning, way less cleanup, and I have more for future work. Of course, brushes are not needed for the dipping method.
Location: WORK IN A WELL VENTILATED AREA!!! I did it in my garage with the door open and fan blowing out. Somewhere outside is ideal. Also, the fiberglass cloth/mat and resin can get VERY MESSY! Work in an area that you can get messy. If you don't have something like that, lay down cardboard over the entire work surface and around the floor so you don't ruin it with drips of resin. I made a makeshift table out of some old plywood and 2x4s. Also, you'll get a lot of stray strings working with the cloth. Have a shop-vac around to clean up. I also had a "drip box" under where I worked so it would catch any cut-offs and resin drips. Helps keep the mess to a minimum.
That's about all I can think of, so I hope this helps everyone!