Some useful tips:
1. Make us of real beach things whenever you can. Sea shells and sand are two things you can use in many ways. Gather a bunch of these either from the beach or through a store. Sea shells are sold as decorations by several companies.
2. Collect beach wedding favors, decorations and other supplies from stores. Use these with the decorations you plan to make yourself.
3. To create your own beach wedding decorations, fill candle holders or glass jars with different colored sand and sea shells. Use the beach candles and other favors you find at the stores with them.
4. To add fun and color use tiny beach favor boxes and other items like sand buckets and shovel to help add to your theme.