Fair skin provides intense contrast to brunette hair. A woman or girl with brunette hair and fair skin needs intense colours in order for her to not look washed out. If there is no red highlights to the brunette hair, then she is considered a "cool" colour and should follow some guidelines to avoid looking too pale.
A "cool" brunette with fair skin looks best in jewel tones. Wear colours that are deep like emerald green, deep blue, true red or black. Think about the vibrant colours that gems come in and stick with those colours. Any pale colour such as peach, pink, salmon or baby blue will make your fair skin look washed out. If you have some white tops in your wardrobe, try to wear vibrant coloured scarves around your neck. The deep colours add colour and depth to your skin and bring light to your eyes.
You can wear bright coloured eyeshadow to match the colours of the clothing you are wearing. Wear the jewel tones, but don't apply the colour too heavily. Wear brown eyeliner and mascara, not black. Avoid any pastels like pale pink or baby blue. These colours will look washed out on you. You can also wear icy colours such as ice blue and silver. Wear a touch of pink on your cheeks and bright pink or light plumb on your lips. This adds colour to your pale face. Avoid very stark colours such as deep red and earth tones.
Hair and Jewellery
If you don't have reddish tones in your hair, you could add shades of burgundy or bordeaux to your hair colour. You could also try adding intense shades of brown, or colouring your hair to an intense colour. Do not dye your hair stark black -- that would be too much contrast with your fair skin. You could highlight your brunette hair with honey or wheat colours, or try ash blonde highlights. Stay away from yellow, bronze or copper red tones. Silvery jewellery looks best on you.