Usually, people will put 1-3 slits in each eyebrow. Thicker eyebrows will generally look better with more slits, so consider the thickness of your eyebrows when choosing your number. Traditional eyebrow slits are usually made towards the outside of your eyebrows.
Only move vertically. Try to avoid any side-to-side motion. If you are doing more than one slit, start with the outside corner and work inward.
Concealer will make the shade of your eyebrow slits match the shade of the skin tone around your eyebrows. You can use an applicator brush or your fingers to rub the concealer in.