There are some differences between the customs of Ashkenzim and Sephardim when it comes to cutting one's nails.
The Rama states that one's nails should not be cut in order. Rather one should start with the ring finger (counted as #4) on the left hand in the the following order: 4, 2, 5, 3, 1. The nails on the right hand are then cut in the following order starting with the index finger (counted as #2): 2, 4, 1, 3, 5. This is the custom for Ashkenazim. In adition, the Mishna Berurah adds that there is an opinion that one should not cut the nails of both one's feet and hands on the same day.
For Sephardim the case is different. Rabbenu the Hida states that the Arizal, himself, used to cut his nails in order and cut both the nails of his hands and feet on the same day and was not concerned about either. The Hida adds that this is the Minhagh Pashut (widespread custom). The Ohr Lesion states that Sephardim may cut cut the nails of their hands and feet on one day and also need not be concerned about cutting their nails in order.
(See Shulhan 'Arukh and Rama, 260: 1. Mishnah Berurah ibid: 6. Kaf Hahayyim ibid: Oth 11, 17. Ohr Lesion, 47: Oth 4)
