im woking on a kampwagon III ausf L , and want to do the tracks. what should i do?

Well, there have been several good threads on this topic. Here is the link to one of them, but if you do a search on "painting tracks", you should get a lot of hits.

Painting tracks thread

Mike

Ilike to drybrush with rust and then add mud it looks good so i'm sticking to that

I like to paint with a dark silver/black mix, when dry wash with a rust colour and then dry brush with silver. Mind you, when I've done adding mud etc it is not worth me taking up too much time with the tracks. Funny, I never seem to put armour on a street diorama, always in a field or wooded area

I like Model Master Burnt Iron Metalizer as a base coat, slighlty rusty hue. Wash of black, Then some steel for drybrushing. Rubber pads, if present are done in Floquil Grimy black.

I use Model Master gun metal as the base color. After it dries I then give it a heavy dose of Rust All followed by a little drybrushed silver. The results look pretty good! :-)

I just mixed some burnt umber oil paint a touch of black and a pinch of talcum power,it dries with a nice rust texture

Fom my website:

Track weathering 101
Tue Feb 19 04:11:15 2002

Weather with washes and drybrushing of your basic earth colors. If you want to experiment without risk, use artist's water colors. If you don't like an effect, wash it off and start again. Mud can be depicted with Celluclay instant papier mache, and it can be colored with watercolor as well. When you're satisfied, spray with clear flat to seal. Clean metal not directly exposed to heavy wear may have patina of rust (though sandy desert conditions will scour all track metal pretty clean). Any parts with metal to metal contact will be polished steel (chrome silver, or silver with a bit of black). If you want a nice final touch, pastel chalks from the art supply store can be ground into a powder and applied to recesses with a sable brush (best if you do this after your final clear coat--the clear flat varnish will float the particles off the surface and ruin the effect). In some modern militaries (the Russians, for instance), the tracks are now painted with black preservative paint, so start with that and then simulate the scoured high points with silver. Rubber components are dark gray when clean, but soon acquire a ground-in dirt color in the field.
In another easy technique, I started using Floquil's Roof Red as a primer. Then I used burnt sienna wash to give it a rust appearance and then a wash of raw umber for a dirty appearance. Then I dry brushed some Tamiya Steel on the raised portion of the tracks for a worn appearance. I thought it worked pretty good for a European Theater and the diaroma I made was a street scene so no need for a heavy coating of dirt and mud. It was also very simple!

I just finished a StuG III A with individual links. I guess the same think could be done with vinyl. 1. Spray with Model Master Gunmetal Metalizer Laquer. (the bottle enamel stuff is bluish and dark). 2. Wash with a black acrylic (Whatever brand...but BLACK) 3. Wash with a thin Rust. 4. Highlight with Steel drybrush. 5. Srcub with pastels (earth tones) 6. (Optional) Mud steps. I used artists watercolor (the tube kind) Raw umber and whatnot. I thinned them down to an enamel consistency and "washed" the tracks. Then (because the scheme is Russia) I concocted (insert sinister laughter) a thick mud paste with the same watercolors, LOTS of pastel powder, coffee grounds (used...why waste good coffee?) and Woodland Scenics static grass. Mix and serve. Made quite realistic clods of mud and grass clumps. Then, not liking the look of "Flat" mud, I touched up some areas with future to gloss up the mud and running gear. HTH

Well you've definetly got a number of paint schemes to choose from. Great job guys.
My 2 cents is to research the tracks and pick the appropriate scheme. There were lots of different track types - rubber shoes, metal cleats, wide, narrow etc etc. Just make sure you get one that's approprate and have at it.