1) make shirts! try and get people to make some logos either by hand or computer graphics. members could buy blank shirts or pitch into a fund and you could buy em. someone could print out some logos onto iron-on stuff and u guys could have a variety of bitchin "surfer club shirts" within the first few meetings.
2) ask the members what they want out of the club and get a feel for how much effort they want to put into it. try getting some ideas from them.
3) spend some time at every meeting planning a weekend surf trip. hopefully enough people at school will be interested so that you could make one at least every other weekend.
3b) also if youve got a beach with good surf and fire pits, you could throw bonire parties during/after surfing and extend the invitation to people at your school who arent in the surf club as well. have them pay like 5 bucks a few days before the party or bring something to contribute. if theres anything ive learned during my years in high school math, its this very important equation:
(music+people+food)² - (drama) = good times
just my 2 cents. i just graduated high school last year and the idea of starting a surf club never crossed my mind. good luck and let me know how it works out for you.