A Backpack is probably easiest to transport, suitcases with wheels aren't best suited to the (ocassionally) bumpy roads Pack a bikini (well the bottom half anyway...) OH!!!!! Mosquito repellant, cream, lotions, spray, citrus candles, after-bite cream, lotions, spray...
There are mossies - and they bite!
Actually most items can be bought from the local supermarkets - but depending on where you are travelling from - you may be able to purchase this more cheaply at home. Sun cream is about the same as UK prices - but you are more likely to get a special offer at home than you will at the shops in Skiathos.