Just a short little guide on my suggestions for upgrading armor accessories:
With armor accessories, one way to go is to have nothing on them except for enhancives. The advantage of this, is you get the full amount of padding from your base armor applied to the covered locations. To go this route though, I dont think you can use warrior resistance or ranger resistance on the armor accessories (I think that halves padding values on the base armor).
The other way to go is to embrace halving and load up the armor accessories. For instance you can put warrior resistance, ranger resistance, WPS damage padding, flares, etc. on the armor accessories. Doing one of these causes padding from base armor to be halved, but doing more than one of them has no further effect. If you go this route, I would aim for 12 points of combat effectiveness on your base armor, that way when it gets halved to 6 on the locations with the armor accessories, you still get 6 points of combat effectiveness (which is the full amount before randomization kicks in).