Zas has made the main point of Tau, they are a very shooting oriented army, Close combat will turn these boys to bits. Sure they have some "Assualt" units (Kroot) but I still have only every used them to tie up the enemy allowing my Fire warriors to escape.
Also, how do you want to play?
Would you prefer to be the static gunline and pound away at your enemies?
Or would you want to be the mobile infantry player who takes FW squads and devilfishes and zooms around the board?
There are plenty of army options for the Tau and the easiest thing to do is choose the models you like the look of most and then go from there, letting us know what your into will help us give you tips on what to take and how to use them.
And any questions you have will be gladly answered by any of the heretics, be in in a thread or by PM