Reht Maryada is the Official Sikh Code of Conduct

The Definition of Sikh:

Any human being who faithfully believes in:

i.   One Immortal Being,
ii.  Ten Gurus, from Guru Nanak Sahib to Guru Gobind Singh Sahib,
iii. The Guru Granth Sahib,
iv. The utterances and teachings of the ten Gurus, 

v.  The baptism bequeathed by the tenth Guru, and who does not owe allegiance to any other religion, is a Sikh.

A Sikh's personal life should comprehend:-

i.   Meditation on Naam (Divine Substance, also translated as the God's attributed self) and the scriptures.
ii.  Leading life according to the Guru's teachings.
iii. Altruistic voluntary service.

To read the Reht Maryada in more detail, please click the link below;

http://www.sgpc.net/rehat_maryada/section_one.html