So, you want to start collecting seashells? Great! Sea shell collecting is a fun and rewarding hobby. But, where do you start? Obviously, the first place you'll want to check is the sandy beach. Empty shells are washed up onto the beach by the tides all the time so this is a great place to start. Unfortunately, this is also where you'll find the fewest intact shells. Often the shells found in the sand have been tossed around underwater by storms and have been cracked, broken or otherwise damaged. To find the best and most complete shells you will have to check some less obvious places.
Scuba diving is a great way to find high quality shells (to learn more about the ins and outs of it, I highly recommend the books located here). Get some snorkeling gear and goggles that will allow you to see well underwater and check the sea floor near the shoreline. This is where you might find some shells that have recently been abandoned. You will need to be able to see clearly underwater to see these shells since they will most likely be camouflaged. Also, since they're so recently abandoned, they should have little to no damage. I would recommend reading up on the shell creatures that you're most likely to find at your local beach so you know where they typically hang out. This will give you a good starting place on where to look for these recently discarded sea shells. You might even find a few other interesting things... like shark teeth!
A few places underwater that typically have a lot of shells are near octopus homes (you will see a lot of broken, discarded shells near an octopus home). You will probably also have a lot of luck near places where the shoreline makes a crevasse like a 'V' or 'U'. Again, you will find a lot of broken shells and pieces of shells here. Search through the rubble and you will probably find a nice treasure.
At low tide, you might have some luck digging around in the mud flats. Follow the trails left by mollusks and you will probably find their discarded shells. A small shovel or rake will help you dig.
Another great place to look is on a rocky coastline a few days after a big storm. When a storm comes along, the little shell creatures get tossed around and they are sometimes tossed on the rocky areas. There, they get themselves stuck in between a few rocks. Wait a few days to allow nature to take it's course then go pick up the beautiful, fresh shells for your collection.
A good general tip for seashell hunting is to hunt on beaches that have few people. There will be less people picking up and/or stepping on the shells and you will be more likely to find a great shell. Try to locate the spot where waves crash before rolling up onto the shore. This is where the waves will be depositing the most shells before eventually washing them up onto the shore.
Hope these tips help! Good luck and happy hunting!