I did my board the other week and used Kinetix R104. Its good stuff but a bit expensive for 6 litres! See links. You probably only need 50 or 100 ml.
http://www.atlcomposites.com.au/atl_composites/epoxy_products/laminating/kinetix__r104_surfboardwww.shapers.com.au/category13_1.htmA few tips I can think of:
1. Don't sand back too hard, it will take the paint off.

Just smooth off the old stuff unless its dis-coloured or coming off.
2. Use a foam roller and make sure you roll out the ridges you sometimes get when you try to roll too much resin.

If you don't you'll see lines where more sugar sticks.
3. The thicker the resin the more sugar that sticks and the rougher the finish
4. Apply lots of sugar. You have enough on when it stays white, then maybe add a bit more!

2 or 3 kgs should be OK, maybe have another kg on hand.
5. Remove masking as soon as you finish applying the sugar. Then leave and don't touch for 24 hours, it can take a while to go completely hard
6. Sweep off excess sugar, then hose rest off outside on the lawn.
7. Be careful on the first few sails, it will take skin off. Acrylic dust would be much better, does anyone know where you can get some?
Also
www.basicwindsurfing.com/how-to-repair-the-windsurf-board-grip.phpwww.boardlady.com/nonskid.htm