IT IS SUNNAH:
1. To trim the fingernails and toenails.
2. To clip one's moustache when it grows long. The most one should clip is enough to show the pink of the upper lip. Plucking it out or shaving it off is makruh (offensive)
3. Shaving one's beard is unlawful according to the Imams Hanafi, Maliki and Hanbali. Imam Shafi'i wrote two opinions about it, one that it is offensive - which is the minor opinion, and the other that it is unlawful to shave. It is unbelief (kufr) to turn from the sunnah in order to imitate non-Muslims when one believes their way to be superior to the sunnah. This fact is a common misconception of modern Muslim men which must be rectified, as their Imaan is at stake.
4. To remove the hair of the underarm, nostrils and pubic area.
5. To line the eyes with kuhl (an antimonic compound that one should be careful to see contains no lead), each eye an odd number of times, preferably three.
6. It is offensive to shave part of the head and leave part unshaven though merely cutting some of the hair shorter than another part is not objectionable, though a person must ensure that a "drop-slope" must not be seen e.g. in "GQ" hairstyles etc. There is no harm in shaving it all though this is not recommended except for the rites of Hajj and Umrah.
7. According to the Shafi'i school of jurisprudence, circumcision is obligatory for both men and women. For men it consists of removing the prepuce from the penis, and for women, removing the prepuce of the clitoris i.e. not the clitoris itself, as some mistakenly assert.
8. It is unlawful for men or women to dye their hair black, except when the intention is for the purpose of jihad as a show of strength to disbelievers. Plucking out grey hair is offensive. It is sunnah to dye the hair with yellow or red. It is unlawful for a woman to cut her hair to disfigure herself for mourning, though if done for the sake of beauty it is permissible as per her husband's wishes. It is sunnah for a married woman to dye all of her hands and feet with henna (a natural red plant dye). However, this is unlawful for men to do so unless it is needed e.g. to protect from sunburn.