If you're looking for some variety in your running training, a beach is a great way to get that. One thing to consider when running on the beach is that it's going to be a different terrain, then maybe if you're running at your local track or on the roads. It's going to be a little bit more challenging.
You're going to be more on the ball of your foot, because you're going to be wanting to take smaller steps to get through the sand. You're going to be engaging your calf muscles more, so be aware of that. You might have to alter your run because of that. Maybe on a regular basis, you're running for 20-30-40 minutes out on the roads.
You might want to cut that down 5-10 minutes, because it's going to be a little bit more of a harder workout. To make it a little easier try to run closer to the water. The sand is going to be more compact, and it's not going to be as hard to run through. Also, be aware of what time of day you're running.
Try to avoid the later morning, early afternoon when most people will be there, so that you don't have to fight through the crowds, and also, if you're not familiar with the beach that you're running on try not to run barefoot.
You're not really sure if there is maybe broken glass, some sea glass. You never really know what's there at the beach, so try to keep your running sneakers on, as tempting as it might be to run barefoot. If you do have a beach nearby try to get over there, so that you can have a change of scenery.