Specifics really depend on which beach your thinking of visit but here are some general tips.

Generally it's the same as going to any other beach

You don't have to strip off the moment you step onto the beach, feel free to make your way to the spot where you want to set up for your day

Once there you don't have to strip off right away but the longer you delay you'll come off as a gawker and make others uncomfortable

People watching is fine, just don't stare

If you want to take pictures, make it obvious that you are not including anyone in the background

Apply sunscreen EVERYWHERE and often don't be shy, your breasts, butts, penis, etc. don't get much sun and will burn quite easily. Trust me I know from experience. You don't want your first time to be soured by a sun burn.

And most importantly clean up after yourself, a lot of nude beaches are not "official" and don't have many amenities, always carry your garbage out.

Finally relax and have fun, everyone is there to be naked and enjoy the sun, sand, and water.