A crew member is someone who supports you in which ever their role is, for example a tailor will copy your current Outfit and set it as crew uniform, or set it to the default protectorate clothing, an engineer will gain you 10% fuel overtime.
Crew members will act the same way as normal npcs, walk around your ship and interact with your furniture.
Crew members don't need micro-managing as they don't have any needs or quests to do as of 1.0
To get a crew member, you must explore. Some NPC's will offer you quests in exchange for them joining you, if you are sent to kill a criminal you may have the chance to spare him and make them a part of your crew too.
The job role of a bandit.