After reading this post about 5th edition tactics regarding troops and why you don't need them. Instead of attempting to cling to objectives his tactics focus on annihilating the enemy with powerful units.
When you consider that Tau troop choices are relatively costly and fragile, fielding large numbers of them is obviously a bad idea. Sure, you can claim objectives, but your points would be better spent on more effective units such as Stealth Suits or Battlesuits to gun down the enemy and boot them off the objectives.
However, as a Tau player who isn't very effective in close combat, this is a cause for concern. Thinking back to my game at the weekend, I wasted a whole turn of shooting by putting everything in reserve. Perhaps it would have been better to take a a few long range hits in favour of a few extra railgun rounds into the enemy?