sorry, that's really too vague.
That's like saying, can you make me an army list of the best race and make sure it will always win so that I can just buy them and never lose?
You should play tau in a way that it'll be tailored to your personality.
Like sitting back and shooting? Use lots of railguns.
Like hit and run tactics? Try vehicles and pathfinders.
Like the barbaric nature of the kroot? well, use them.