An associate is an individual who works for a crime family but are not "made members". Thus, they are not considered true members of said families. Associates often work as bodyguards in the family rackets. In addition, they frequently carry out oddjobs for family made members in the hopes of being made members and other ranks of made members are underbosses, consigliere, caporegimes, soldatos and enforcers.
An associate can have a wide range of duties but are generally kept away from family buisness unless they are on a track towards being a made man. Duties can range from propretiors of front end buisnesses, bribing police and judges, racket bosses and moles, to carrying out the same duties as a soldiers to being a simple errand boy. This is where prospective mobsters ("connected guys") start out to prove their worth. Once a crime family is accepting new membership, the best associates are evaluated and picked to become soldiers, thus becoming "made-men". This is typically the case if one is of Italian descent, as regardless of one's connections, one must start out as an associate in order to be vetted. But for a non Italian, one generally goes no further than being an associate.
Associates will normally have very llimited contact with family members other than the one he directly works under, especially if he is non-Italian. But if the associate is Italian, he will slowly and carefully be introduced to other family members as he progresses towards being a made-man. In mixed company, one generally refers to an associate as a "friend of mine" while a fellow family member is a "friend of ours."