Will my metal detector work on the beach?

Maybe. It depends where you are going to detect and what kind of detector you have.

My first rule of beach detecting is do NOT take your detector near water if its not waterproof. Too many people have ruined there machines doing this. 

If you are talking about a fresh water beach then most detectors will work on the wet and dry sand. But in a salt environment, this is not the case.

On the dry sand, any machine will work just fine. So if you are visiting the shore for the weekend or week your home detector will work great on the dry sand.

On the wetsand and water however this is not the case. On the wetsand and water you need a multifrequency machine or it won't work. Sure you might be able to change the settings and detect and inch or two but more or less you need a multifrequency machine and there are only a few machines out there that have such a function and they are expensive.

Some non waterproof ones include the Fisher CZ3D, Minelab Etrac, Minelab Sovereign. These are great but not waterproof.

The waterproof machines are the Whites BH300, Fisher CZ21, Minelab Excalibur, and Minelab CTX. That's it. 4 machines which are waterproof and multifrequency. If you have an el cheapo machine that has a 'salt' setting it will not work. It needs to be multifrequency and these are it as of writing this post.

Now another option is a PI machine however if you are asking this question, a PI is probably not what you are looking for. They are great beach machines but they require you to dig everything. This is usually not very good for beginners. They are more of a specialty machine for certain highly mineralized beaches, dives, and times when the beach is sanded in/clean. They are great machines for experienced detectorists that know they want a PI.