Firstly, the rules for guys and girls are different, although there are always people who try to break that rule. Don't let that be you!
So the first thing to mention is that the hard work starts way before you hit the beach. If you really want to look cool, investing time in the gym to get that "beach body" is a good idea.
But let's face it, not all of us have the time or willpower to stick to a gym routine and gruelling diet, so here are some other practical tips:
Bring friends to the beach
Everyone looks cooler when they're having a good time with friends. You'll appear more confident and outgoing, and everyone will envy the photos you Instagram and subsequently post to Facebook:
Invest in some nice swimwear
Take your time to find the swimwear that best compliments your body type. People often make the mistake of thinking "swimwear is swimwear" and don't pay it as much attention as regular clothing.
Don't fall into that trap!
Depending on where you live, you may not be able to don your favorite beach outfits as often - but it's worth investing some time (not necessarily loads of money) in picking your swimwear.
Certain designs will look great on some, and not so hot on others - regardless of whether they're purchased from a designer store or your local thrift store.
Don't get so hooked on wearing a certain brand or design when you might look cooler trying something new out.
Guys: Board-shorts VS "more fitted option"
It's an age-old debate, and one that doesn't really have a definitive answer. As long as you steer clear of the "banana hammock" look, you should be ok.
Board shorts tend to have more variety in the patterns, with funky Hawaiian and Tiki themed shorts proving popular these days.
Asking a girl's opinion is always a good idea too, just not your mom please.
Girls: How much to reveal
There's a huge journey from conservative one-piece to g-string, and whilst it may seem logical that more revealing = sexier, I don't think that's necessarily the case.
From a man's perspective, a good-looking girl will still turn heads no matter what she's wearing, and often going for something that reveals a "teasing" amount of flesh without giving too much is sexier than "over-flaunting".
Secondly, I remember being at a topless beach and, after the first ten minutes, the site of boobs actually becomes... Normal. As a guy, it's a hard thing to get your head around.
It always amazes me how, a pair of shades that look great on a friend always make me look like Willy Wonka.
Perhaps the best idea would be to take a look at some celebrity magazines and find that one celebrity that people are always telling you that you look a bit like.
Check out what brand they're wearing, and this might help you narrow down your search.