Most islands can benefit from education supplies, pens, school books
etc. One thing we got asked for a few times is children's reading books
as they had very little material to encourage kids
to read. Fishing
hooks and line are always welcome. Medicine can be a thorny issue in some places but paracetomol and antibiotics in date are worth carrying. The islanders will generally take whatever you offer, even if they don't need it so try to conduct your own assessment. For treats for the kids
think popcorn, not lollies. Post cyclone Pam here everybody was donating rice. Bad idea, the incidence of diabetes is likely to skyrocket with the reliance on rice now for very little nutritional value. You are unlikely to encounter any serious mal nutrition but lentils would be a more valuable contribution.
Most importantly, trade
instead of giving wherever possible. This allow the locals to retain mana as well as helping to stem the culture of welfare instead of self reliance which is rapidly establishing itself.