I'm not sure what's available to you guys over there, but I use a 4lb (2) part foam from either SilPak or Burman industries in L.A. IF I foam aany item outside the mold, I take my time and do small pieces at a time.
Bisceps, Triceps, forearms, etc... VERY small portions.
Quads and Chest are my biggest mixes.
Just lay the skin flat, mix the foam and pour it onto the various areas. Once the foam starts to expand... DO NOT TOUCH IT> you will pop the bubbles forming and cause the foam to go flat, losing any "fill" into the area. You then have to wait for it to dry - pull that out and try again. Also, if you poour into a area and it's not quite what you wanted.... you can either mix a smaller portion and oour around it, or simply tear out a little if it's too much.
Lasly, in the rib section, and along the sides of the chest and legs, I pour a very thin layer of foam just for some definition. You don't want it too thick, jsut to give the skin some support and look good.
Once your happy with the foam in a specific area, let it dry a bit, then sprinkle some talcum, (baby powder) over the area. THis will keep you from sticking to it as you are foaming hte other areas.
Hope this helps... but of course, this also assumes you can obtain a 2 part foam over there. It's basically the same foam I use to fill the masks.
Good Luck
E-O