The Brucca Method for doing tracks.
The below step by step is intended for non-working rubber band like tracks. If you want to do workable tracks like Frui’s or Model Kasten type, look below.
Step 1: Painting: Paint the tracks a Dark brown color. I used a mix of Tamiya Red-Brown and Black.

Step 2: Dry Brushing Silver: Dry brush the top side of the track with a silver metallic color. Also do the same for just the outside ridge of the track on the inner side of the track.

Step 3: Adding Pigment: Using a pigment, in this case, Star Dust Light Earth, put the pigment in the center of each track link space using a #1 round brush. Try to keep it towards the center of each link and away from where the links meet. Also, add different pigment colors on top of the first color already on track to add contrast. After applying it, gently tap down the pigment in a dabbing motion to help it stick and mix the different colors.

Step 4: Cleaning: Blow away any loose or extra pigment. There should be a lot of extra pigment on the tracks. Make sure you gently blow it off.
Step 5: Blending: gently brush the pigment toward the edges of the track spaces. We are trying to blend the pigment color with the dark brown color of the track.

Step 6: Enrichment: Repeat steps 3-5 carefully to improve color contrast and look.
Step 7: Adding Mud: On the top side of the tracks, using a water mix of Star dust light earth, sandy dust and refined soil, apply the simulated mud to the tracks. Try to keep it away from the holes in the track for the drive sprocket teeth, because the water will remove what we did in steps 3-5 on the opposite side of the tracks.

Step 8: Sprinkling: Using different shades of mud pigment; such as Light earth, Sandy dust, Mig’s European dust, sprinkle the pigments one at a time on the still wet tracks. Then, let dry. I place it in front of my air conditioner to help it dry quicker.

Step 9: Finger Brushing: Once the tracks have dried, run your finger across the top of the tracks. It helps if your finger is slightly wet. We do this to clear any pigment or dust fron the metallic worn parts of the top of the tracks.
The above step by step is intended for non-working rubber band like tracks. If you want to do workable tracks like frui’s or Model Kasten type, do the following:
Step 1: Painting: Paint the tracks a Dark brown color. I used a mix of Tamiya Red-Brown and Black.
Step 2: dry brushing Silver: Dry brush the top side of the track with a silver metallic color. Also do the same for just the outside ridge of the track on the other side.
Step 3: Adding Mud: On the top side of the tracks, using a water mix of Star dust light earth, sandy dust and refined soil, apply the simulated mud to the tracks. Try to keep it away from the holes in the track for the drive sprocket teeth, because the water will remove what we did in steps 3-5.
Step 4: Sprinkling: Using different shades of mud pigment; such as Light earth, Sandy dust, Mig’s European dust, sprinkle the pigments one at a time on the still wet tracks. Then, let dry. I place it in front of my air conditioner to help it dry quicker.
Step 4a: Finger Brushing: Once the tracks have dried, run your finger across the top of the tracks. It helps if your finger is slightly wet. We do this to clear any pigment or dust from the metallic worn parts of the top of the tracks. You can also use fine grit sand paper if your tracks are the white metal type.
Step 5: Re-painting: repaint the inner side of the tracks because it will probably look like a mess after steps 3-4.
Step 6: Adding Pigment: After the paint has dried, Using a pigment, in this case, Star Dust Light Earth, put the pigment in the center of each track link space using a #1 round brush. Try to keep it towards the center of each link and away from where the links meet. Also, add different pigment colors on top of the first color already on track to add contrast. After applying it, gently tap down the pigment in a dabbing motion to help it stick and mix the different colors.
Step 7: Cleaning: Blow away any loose or extra pigment. There should be a lot of extra pigment on the tracks. Make sure you gently blow it off.
Step 8: Blending: gently brush the pigment toward the edges of the track spaces. We are trying to blend the pigment color with the dark brown color of the track.
Step 9: Enrichment: Repeat steps 3-5 carefully to improve color contrast and look.
Thanks for looking, all comments are always welcome
Thanks
Nicholas