Luggage and bags:
A small backpack is sufficient and pack it with water, especially if you go out of the city...doh.
Clothing/Shoes/Weather Gear: Sunglasses...definately ;oP , shorts , a pair trousers and a nice shirt that is if ya wanna go clubbing and dance the merengue, salso, con or casino.
The locals dress up...so why don't u ;o)
Toiletries and Medical Supplies: Definately bring some toiletpaper [trust me, do NOT forget this] especially if you are from a western country. Also a small medical kit will do just fine.
Photo Equipment: Allthough you will be able to find batteries [all types] and films. It would be smart to bring some xtras along, unless you want to pay special prices for it.
Camping/Beach/Outdoor Gear: Outdoors? Don't go sleeping outdoors, trust me...the mosquito's will kill ya...they are BIG mf ;oP
Miscellaneous: 1. A flashlight or 2, power outages are NOT rare in Cuba.
2. A copy of your passport [security issue]
3. A small pocket knife
4. A portable music device [pref with radio] with some speakers, great for the beach or for your roadtrip should your car-radio get broken or 'stolen'.