Sunburn!
Check out the venue. One of the hosts for our non-landed club has a pool and deck on the sunny side of his house, and opens only the outdoor area to the club; the few tiny patches of shade aren't big enough for a conversational circle, and I would think twice about going there again for a mid-day event. People do wear t-shirts and hats into the pool there.
Where you have shade, just stay in it; visit the pool or other sunny areas in measured ways. You will not be alone.
If you can start been out in the sun just in the early morning and in the evenings so your body starts getting used to been exposed to the sun and starts loosing the whiteness and over the summer you will be able to stay out longer and depending on how strong the sun is it most likely still be best to stay out of the mid day sun.
I would take a look at the website pics of the resort you plan to visit, and bring the gear that is most appropriate based on all the good suggestions above. Sunscreen, hat, sunglasses for sure.
You may be able to skip an umbrella if the place has lots of shade. Many resorts have pavilions or other areas with roofs. Check out the place you plan to visit. Have fun and tell us about your first experience.
Use a good sunscreen SPF 50 or higher. Especially when you get closer to the equator. I learned my lesson in Costa Rica. There you need SPF 70 plus. Had to gradually work on tan about three weeks before my vacation. Bring a good sun hat also. Good luck!