Accent and accessorise for a relaxed scheme
Red is a popular accent colour which can be used for cushions but you could use other colours such as orange, turquoise or even navy blue. These colours will add a 'zing' to your scheme.
Natural items such as shells and driftwood complete the scheme but don't go overboard with these as it will make the design appear too contrived.
If your room doesn't have lots of natural light then use mirrors to reflect and bounce the light around your room.
Flooring should be from natural materials - coir matting is hard wearing, painted floorboard are a practical choice and so are tiles.
Everything about a coastal scheme should be relaxed so mix and match cushions using striped fabric, plain fabric and seaside fabric.