Don't comb the mane out, but use a people nylon toothed styling brush instead. Always work from the bottom up to the roots when grooming the mane. There are a number of clipping styles for donkeys or mules. The alternative is roaching the mane down to the neck with a photo or trace the shape of your mule's neck from a photo and experiment with different styles to see which will suit him or her best. A long neck can be enhanced by a longer bridle path, and an upright curved mane can help a thin neck.
Donkeys tails have short body hair over most the length, ending in the longer switch.
The tassel hair can be left natural, banged across the ends, or may be shaped or belled. Mule tails are often shaved down a few inches from the top, then left full and long. The length of the area you shave, as with the bridle path, can enhance the hips. Always take small amount off when trimming - you can always snip a few more hairs off, but you can't stick back on the ones you have already cut If your mule or donkey is in a shed, slick summer coat, daily grooming will help keep it looking good for the show season. Limit bathing, as it strips away essential oils in the hair.