Don't forget your travel insurance !!
If you are arranging return transfers, make sure you get a telephone contact number for the taxi firm so you can call them the day before you are leaving your resort and make sure they've remembered you.
Have you arranged accommodation direct or with an agency?If direct, e-mail the hotel/apartments and tell them when you'll be arriving. If you've used an agency, ask them to contact the hotel for you and to confirm that they have done so. Print off their reply just in case of problems later.
Print out the address of your hotel/ rooms just in case there's a language problem with the taxi driver.
It's a bit nerve-racking the first time but you'll probably find that things run as smoothly if not smoother than with a tour operator.Good luck and instead of worrying, think of the money you've saved !