1. recovery gear - always go prepared for the worst (includes tools/water/food etc)
2. atrac - easy and cheap
3. armor - don't leave home without it. lifting / tires will get to places where you wish you had armor first.
4. comms - if you don't have it, you're missing out on the fun.
5. lift
6. tires
7. lights (if you do a lot of night runs)
8. dual battery
9. winch
10. your first child and your second child

(here's where your mind goes wild and you start buying everything!)
you get the pic. whatever you do I would make sure you have recovery gear because you'll need it at every state of the game. after that 2 and 3 are a close one but I would do 2 and 3 prior to lift/tires. The key logic behind this is the fact that you will appreciate your FJ more by taking it out virtually stock and understanding the limitations of the vehicle. once you get acclimated to the FJ you can then venture by adding some improvements (lift/tires) to gain more confidence in doing harder trails. If you don't, you'll miss out on the appreciation for your fj.
good luck!