A popular trend among crossplayers is the super arched aka ‘angry’ eyebrows. If you browse through a couple pages of KSPRE, you’ll find that every, I swear, every crossplayer has these angry eyebrows. I use this method too~
But why would a cosplayer want to look angry?
Normal arched eyebrows can look too feminine as it gives a ‘softer’ frame of your T area (forehead+nose). With the angry brows, it appears to be a lot sharper and thus looks more manly.
Other cosplayers’ examples:

Girl vs Male
The brow thickness can vary from character to character~ The angle of the angry brow can also change. The more slanted it is, the tougher you look. The flatter it is, the calmer and kinder you appear.
Drawing for reference~
For the how to: The last image depicts the most basic angry brow (and a normal eyebrow for comparison). Sorry for my poo drawing haha The front tip should be the thickest and thin out towards the end. I advise to start drawing the angry brown from the tip of your own eyebrow and draw a faint straight (and angled) line, so you can change it if needed without hassle. Then darken it and thicken the brow accordingly.
Despite how the brows in the drawing look kinda sketchy, avoid that (that’s cuz of my bad doodle skills orz). The brows look better with a clean line~
Close-up of my makeup tests:

Remember that the brows should always match the wig color. If you do not have the right color, black works too.
I personally suggest to avoid angry brows for female cosplay, unless the character is more tomboy or boyish. But eh, it seems like most cosplayers in female or male cosplays do it anyways. orz
To get the right shape and angle takes practice and words can only do so much, so good luck, fellow cosplayers!
Photos belong to original cosplayers. Please see KSPRE for the sources.