First and foremost - hydration. Your skin, hair and lips are going to be very dry from salty water so hydrate, hydrate, hydrate!
1) Drink a lot of water (2-3l)
2) Moisturize your skin whenever you can (2-3 times)
3) Get a lip balm (preferably with SPF)
4) Don't wash and blow dry your hair every day
It is very important to apply your SPF over the whole body and face every two hours. Use SPF 30 and don't tan all day long just so you can get that fast tan you wanted the whole year.
Be patient otherwise, your skin will start flaking, you won't get that nice bronze tan and you'll get sunburnt. Try tanning before 12 am and after 4 pm, in other words, avoid the sun between 12-16h.
Also, as I said, moisturize your skin with some body cream after every shower and if you get sunburnt moisturize even more on those spots.
One of Elle's recommendation for face SPF is Nivea BB cream with SPF. I tried it and it's great and very light on the face and also moisturizing!
For lips, I recently bought Kiko drop lip balm with scrub and so far so good. Also, it's small so very convenient to bring with you.
For hair, I recommend some light shampoo without parabens, conditioner which you won't rinse totally and a hair mask you'll bring with you to the beach (conditioner will work too).
Then every time you get out of the water, wash the salt out of your hair and then put a hair mask or conditioner and leave it in for soft and shiny hair until the next round of swimming.