After writing the pinning guidelines I thought I might share the basics of green stuffing. What's greenstuff? It's a two part epoxy that you can use to fill gaps or sculpt entire models. The stuff is fantastic. I'm no expert, but a little greenstuff goes a long way.
Step 1: Have the appropriate tools. You'll need the basics. Gale Force 9 makes an excellent 3 piece set that I can't recommend enough! Check them out: http://www.gf9.com/store/product_info.php?cPath=37&products_id=256
Step 2: Fill a cup for water. This might be one of the most important steps. You will see why shortly.
Step 3: Mix your greenstuff. Remember a lot goes a long way, and patience is a virtue. Mix even amounts until the Blue and Yellow turn, you guessed it, Green!
Step 4: This step varies a bit, but lets start with filling a undesirable gap. Notice the gap in this Vargulf's shoulder. You can even see the pin!
(Step 4 continued) Apply a bit of greenstuff to the shoulder area.
Step 5: Dip your tool in the cup of water! The water prevents the greenstuff from sticking to the tool!
Step 6: Using the spoon headed tool work the greenstuff along the joint. Don't smooth the greenstuff flush with the two joined pieces. You will want the greenstuff slightly raised to do the texturing.
Step 7: Using the variety of tools texture the gap to match the surrounding areas. Flat areas are easy! Just follow the contours of the model.