One of the best ways to add a coastal feel to your home is to include natural elements. Whether that's in the form of driftwood (see this post), seashells, coral, or sisal/jute rugs, it's easy to achieve a cohesive, fuss-free look.
One coastal home decor item every beach loving person can easily include in their home is sea fan wall art. It makes a BEAUTIFUL statement piece and is easy to incorporate anywhere with (typically) just a few colors within the art.
Unframed options are a great affordable option as well.
I LOVE this beautiful sea fan a family member got for me on an overseas vacation trip and put it in a dark stained shadow box. It's such a special piece in our little beach house. :-)