So, I'm thinking of designing a tactical hoodie that I can sew together myself. Some of the considerations:

1) Reduce the amount of seams that can give way.
2) Use "french seams" when possible for added strength.
3) Specific fabric depending on weather (ie. Wool type for winter, Cotton blend for summer)
4) Specific fabric color depending on terrain (ie. camo for wilderness, flat color for urban)
5) Have zippers under the armpits to let heat/moisture dissipate easier, such as on US military gortex jackets.
6) Adjustable wrist cuffs, again taken from the gortex jacket.
7) A velcro "split" near the waist area to go around holstered weapons.
Pockets on upper sleeves to hold items, maybe like bomber jackets for writing utensils, etc.
9) Pocket on front for hands that also has a pouch with velcro flap.
10) Waist band that is adjustable.
11) Zippered neckline.
12) Long enough to fit over EDC beltline kit.

Any other ideas that WOGs could toss into this idea?

Maybe something like this would help you out. 

http://cgi.ebay.com.au/USMC-US-Army-Parka-Jacket-Waterproof-Olive-Drab-OD-S_W0QQitemZ350110715678QQihZ022QQcategoryZ159031QQtcZphotoQQcmdZViewItem
^I have had this on my list of kit to reverse engineer when I get my sewing machine, maybe you'll beat me to the punch on this one. 

I would suggest sewing buttone to the inside so that the liner from a M65 field jacket can be added. 
Also, an internal pocket in the left breast just big enough for a multitool would be nice.

fire retardant would be nice, Aramid would be even better (although probably difficult to acquire).