1)Always remember dark lips can show the flaws in your lips easily. They need to look smooth and flawless. To get this perfect look make sure you exfoliate your lips well.
2) Using a lip liner is a must, when using a dark lip colour. Start from the outer corners of your lips towards the centre. This would help you outline your lips to even both sides and help you lipstick stay in place preventing it from getting smudged.
3) Find the right shade of dark lipstick. Always keep in mind that although some colours look good on catalogues, they might not suit you so much.
4) Dark lip colours wear off quickly, which get quite noticeable too. Use a good brand for dark lip colours so it will last longer.
5) For dark skin tones deep plum, berries and plums would look great during the day but women with lighter skin tones can use these colours for evening wear.
6) Try wearing a neutral clothing choice, it would go well with the dark lipstick shades.
7) When going for dark colours on lip, try to keep your eyes natural with minimal make-up. This would enhance your lips even more.