1. For more defined waves, it's necessary to use a curling iron and a whole mess of products to keep your hair looking extra voluminous and tousled. Something like this iron from Not Your Mother's makes it super easy for you to give yourself loose waves. (Like, I am a beauty product infant and even I can do it.) For a natural look, make sure to leave the bottom inch or two of hair out of the curling iron and gently brush out your curls afterward; if you don't, there's a strong chance you'll end up looking like Shirley Temple.
2. To make sure your hair stays voluminous and very "I just rolled out of bed like this" even when it's 5 p.m., it's always a good idea to use a volumizing spray (duh) or one of those wacky plumping powders. The plumping powders can be a little trickier to get the hang of (and they feel sooo weird on your hands), but rubbing a tiny amount into your roots will give your hair a lot of textured volume. It'll look like you spent hours letting your hair whip around in an ocean breeze, when really all you did was sit on your bed and watch Netflix.
3. If you're looking for tousled waves that take almost literally no effort, this Beach Babe Texturizing Spray from Not Your Mother's will be your new best friend. It's supposed to be used on damp hair, but I've found that it works just as well on dry hair (in case you're running out the door), and you don't need a lot of it. If you have super straight hair, spritzing some of this onto dry hair and then using a curling iron before setting with a light hairspray is a good way to help waves last longer.
4. If you want to do everything you possibly can to get beachy hair, this Beach Babe Shampoo (also from Not Your Mother's) has Dead Sea salt mixed right in it, so it gives great volume and texture, even before putting any products in your hair. Anything with salt as a main ingredient will obviously give that perfect beachy look, so using these sprays from Captain Blankenship and Brooklyn Beach on top of the texturizing shampoo will do wonders without having to fry your hair with an iron.
5. If you're not in a rush, another good way to get beachy hair is to spritz on some of the aforementioned sea salt sprays or a texturizing spray and then pop your hair up into a few buns. After sleeping on them overnight, you'll be left with perfectly tousled hair with minimal work. Great for those of us who are not morning people.