Severely bruised wallet due to even more spending in boards and smaller kites for foiling
Apart from that the usual, had my lines tangled in the foil a few times, but nothing major as normally you're in a smaller kite. A few close calls though, so even today being much more proficient I still wear helmet and impact vest.
When learning I used to check the depth with my feet to make sure it was deep enough to not hit bottom with the wings even if I sank the board with my whole weight. Scraped a sea urchin doing this and had some 20 of those spikes...
Never had any problems with ankles and food straps as I took them off quite early. In my opinion you don't really need them unless you plan on going with faster foils. The only 'difficult part' to learn is the waterstart but you can do it in one session and then it's just natural.