Tau are in an interesting place in 8th. It's easy to build a top tier competitive list, and it's easy to build a doormat list that your opponent will rofl stomp. It's less easy to build something in the 50% - 75% competitive range that seems to be the OFCC list ideal. However, there are ways for you as the player to greatly impact the stompiness of some of the units.
Most of Tau's hyper-power comes from synergy. 5 pulse rifle warriors unbuffed at 18" range is 5 s5 ap0 shots, hitting on 4s, woundong on 3s, no biggie for almost any opponent. Those same 5 FW fully buffed with drone and HQ support makes them 15 s5 ap0 shots, hitting on 3s re-rolling 1s, wounding on 2s. That becomes problematic for most opponents.
Take the riptide, it's our best unit, but maybe only nova charge every other turn, or maybe dont use C&C node stratagem with it.
Your good attitude will be your best weapon at OFCC, and your ability to strategically hinder your own army's capabilities may be your second best weapon if your opponents army warrants it.
Build the list strong, make it weaker through intentional poor synergistic play, adjust to good synergistic play if opponents army and play warrants a power increase is how I would approach it.
Good luck and have fun most of all!