How to avoid one of the biggest vector mistakes by Austiniousi
Hope it helps in some way or another
Erhm, AJ with Raritys' tail and Pinkie with a new hairut..?
The tutorial here is great! I learned not to do the "old" tapering technique. Now:
GIMP is not a vector program. Neither is Photoshop. The point about stroke width modifications you brought up is solved in Illustrator CS5 (Stroke Width Tool [I know...I need to update my leg tapers!]) and Inkscape (PowerStrokes)!
If you insist on using other programs, try using the "circle method". Create fixed diameter circles and place them around your strokes. Then adjust the handles to match the outside of each circle. A limited example can be seen here.