My main advice for guys joining an online dating website like OK Cupid is to be yourself!
Trying to make yourself sound and look like a more attractive version of yourself may attract more interest to begin with, but chances are it won't be the right kind of people. For you, anyway.
Pretending you've read pretentious books and films might not be a good idea if actually you enjoy going to the football and watching Netflix. And might put off people who actually like to do the same as you.
Also it's good to be complimentary, but stop short of using clichéd "lines".
Be original, don't be cheesy or sleazy, nobody actually wants that. Instead, ask people questions about things they've said on their profile - it shows that you actually read it, and are interested, and didn't just look at their pictures!
Online dating, like regular dating, is a little bit of trial and error.
See what approaches work, and what doesn't. But definitely don't waste time pretending to be something that you're not - we've all seen Catfish after all! (And if you haven't, you should definitely check it out before you start...).