I was born in Tahiti then I had moved to hawaii about 15 years ago. Anyway I started surfing in Tahiti about 20 years ago and I just came back from there after 15 years... 1st trip back to my native country. Things have changed a lot and the surfing level and interest had progressed a lot. Unfortunately the local government does not help promote the surfing industry such as the Billabong pro in Teahupoo. This contest is undoubtly one of the most relevant part of the surfing tour. Check out the power and the impact on the the pro surfers there. I'll give you a few tips before you go there:
1) it's better that you contact a travel agency who know the surfing spots in french polynesia before you get there. Tahiti itself has a wide range of spots but consider going to 2 or 3 other islands to really surf some amazing such as in the Tuamotus islands, Huahine, and Raiatea.
2) people are very friendly and a lot of local surfers do speak english. Try to talk to them and know the spot before you get into the water. It might help you save your board or some mean scatches on yourself. If you plan to surf at Teahupoo be sure of your skill. Personally I am confident there with anything less than 4 feet! After that it's a gamble with life and death...
Try other spots like Taapuna, Sapinus, Papeeno, and Papara where the latest world knee board championship was held.
3) almost everything here is expensive... I mean 2-3 times than your local market on the mainland! If you're hungry eat at the roulotte at the Papeete harbor! Great meal at $10. A fresh loaf of bread is only 45 cent and and I usually get a huge sandwich with ham and stuff before heading to the beach.
4) don't get stolen! A lot of tahitian don't have a job (and can live 'happily' without working) have a tendency to steal stuff. So watchout not to leave any valuable in your cars or wherever it's easy to get them.
There are many other advices I could give you but it's a unique place with beautiful people around a colorful environment. People are naturally nice and kinda friendly to foreigners... like in the old movies (mutiny of the bounty!)
Be ready to explore an incredible journey in Tahiti!