Alex -- nice pix!
Beach shots with an SLR camera (digital or 35MM):
For B&W film: Use a yellow or orange filter. I love red filters for B&W, but they might be a little strong for the sun-filled beach. These filters will add emphasis to your subjects.
For color film: Use a blue filter to emphasize the water and the sky -- it'll make a difference! Or, if you're taking pictures of the foliage, consider a green filter.
Whether you're using B&W or color, use a polarizing lens (sometimes called a circular polarizer). This lens increases color saturation, reduces glare, and makes everything stand out more. It's especially good for nature pix with lots of cloud and sky. I keep my polarizing lens on my camera 100% of the time -- I add the other lenses over the top. Why? If I scratch a $10 lens, I'm not going to be very upset; if I scratch my $200 lens, I will cry!
For good all around beach pictures:
Choose 100 or 200 speed film. Avoid disposables that come pre-loaded with 800 speed color film; there's a distinct loss of color quality when you move up to 800 speed film, and there's little need for the speed on the beach. I use 800 only for indoor basketball games, but never without an FL-W filters, which reduces the greenish tint thrown off by flourescent lights.
Remember the rule of thirds -- imagine there's a tic-tac-toe grid across your lens, and place your subject on one of the cross-pieces.
Get close to your subject -- a zoom lens is wonderful.
Don't shoot into the sun -- unless, of course, you want a picture of your subject in sillouette against the ocean. I took some great pictures of my husband on the beach at Thanksgiving using this technique. The sun is setting behind him, you can see the sun's glare on the water, and my husband is walking all alone on the beach. Great pictures -- just be sure you do this on purpose, not by accident!