Comb hair to remove any snarls and, holding the shears horizontally, trim to the desired length. To add some movement and avoid a blunt-looking cut, you can hold the shears vertically and use the point to make very short snips.
NOTE: Always leave your hair a bit longer than you'd like so you have some room to even it out if it looks unbalanced. It's also best to trim your bangs when they're dry so you will have an accurate view of the length.