1. Open up the zip file in your zip program of choice. I don't personally use WinZip, but if you do, be sure to go into Classic Mode, not Wizard Mode. Your window should look similar to this:
2. You need to find out what model it is for. The name of the TGA file (not portrait.tga) should tell you what the name of the model is. If there's a TGA file with a _extras or _cape, you want the other TGA file. In the example above, the name of the model is male_heavy.
3. Double click the text file that is in the zip file. If there are more than one, find the one that tells you which model (or mesh) the skin is for. It usually says 'for the model_name model (or mesh),' where model_name is the name of the model. If it matches the name you got from step 2, then that is your model name. If you don't find a model name in the text file, just use the name gotten in step 2. If they don't match, click here.
If the name of the model is for any of the below models, click here. If it's not for any of the below models, click here. If the model name starts with generic_ click here. If there's a character.nif and/or keyframes.kf, the zip file has included the model with it. Click here if that's the case.
Alchemiss
Alien Warrior (alien_warrior)
Blackbird (black_bird)
Bullet
Darkman
Deja Vu (dejavu)
Dwight Arrow (clint)
El Diablo (el_diablo)
Eve
Gangster
Ice Queen (ice_queen)
Ice Warrior (ice_warrior)
Iron Ox (iron_ox)
Law
Liberty Lad (liberty_lad)
Lord Dominion (dominion)
Man O War (man_o_war)
Man-Bot (man_bot)
Manbull (man_bull)
Mentor
Microwave
Minuteman (minute_man)
Nick Craft (nick)
Nuclear Winter (nuclear_winter)
Order
Pan
Pinstripe
Praetor
Sea Urchin (sea_urchin)
Shadow
Shadow Unmasked (shadow_unmasked)
Supercollider
Sylph
The Ant (the_ant)
Thug1
Thug2