Don’t forget to bring sunscreen and drinking water with you.
On your first day foiling, be prepared to be in the water more than you might be used to! Because you can foil in light wind, you will be uphauling the sail to get going (you can foil in much less wind than you can waterstart in). Falling down and uphauling doesn't mean you are failing - it means you are learning. Dress for being in the water a bit more than usual and be prepared to be out of the harness most of the time on your first day.