Back in Imperial Armor 3, Forgeworld decided that Tau camouflage doctrine usually employs a two-tone color scheme. The camo will rely on natural patterns, often symmetrical. Popular ones on the net use water wave patterns, diffuse stripes, and the like. The Fire Caste does not use contrasting colors, but cadres will use a trim color.
Camo can be tricky to do on models as a good camo will diffuse the lines on your model. That effect makes your model look poor when viewed from across the table. A safe approach, and one I recommend to new painters, is to use a two tone pattern and paint parts of your model in those two colors. Use one of them as your base color. Then use the other as the "trim" color. Good parts for using the trim color are the panel near the engine intake, the exhaust vents on the nacelles and exhaust port on the sides of the cockpit. You may also want to consider the ring around the hatch doors (the one that includes the viewport), the nose panels and possibly the secondary web system.
If you're brave you can try the method described in
IA3 above by applying the lighter tone via an airbrush. If you use a dark color for your base color and a lighter tone for your camo or accents, the model will tend to rise from the table. Conversely, if your primary color is light and you use a darker tone on the model it will sink to the tale. It is very subtle, but it may help you.
Hope this helps!
Edit: I did a hammerhead using a two tone camo scheme similar to the jagged edge found on some urban camo patterns from the old Soviet Bloc. It didn't lok very Tau. Leave the marpat and strong contrasting colors to the Guard.