Paths of the Eldar
After the Fall of the Eldar and the birth of Slaanesh, the surviving Craftworld Eldar realized that their emotions were too potent to be allowed to run free. To control their emotional extremes, the Craftworlds formulated the Paths of the Eldar, as series of goals and occupations that would leave the Eldar emotionally regimented to avoid falling prey to She Who Thirsts. Collectively, the Paths are like a form of Multiple Personality Disorder, where an Eldar will learn everything they can about one role or task, shut it off from their mind when not needed, and reopen it when needed. It is, however, possible to reach a point where an Eldar becomes "lost on the Path", meaning that they cannot shut off that particular aspect of their personality to the exclusion of all others. There are a number of known Paths that can be walked.
Path of Awakening
On this path, an Eldar will learn to better analyze their surroundings. This allows them to see things that others would ignore or dismiss as irrelevant.
Path of the Artisan
This is among the most common Paths, where an Eldar learns to make breathtaking works of art. There exist a number of sub-Paths, such as the Path of the Poet, the Path of the Sculptor, etc.
These sub paths do not necessarily mix well with each other or others. The Path of the Poet for instance is about writing introverted fanfics that no-one is supposed to read, and so the author can become very apprehensive at allowing others to read them.
By contrast the Path of the Sculptor is highly extroverted, and wants everyone to see their work, but can act like a diva even when fairly criticised.
Path of Command
Also known as the Path of the Leader, this is the path that focuses on leadership of other Eldar. Those on the Path of Command become Autarchs, the Eldar equivalent of admirals or generals.
Interestingly this path can be planned, rather than something that occurs naturally as an Eldar accumulates experience from various paths. One can arrive at an Aspect Shrine and make themselves known that they intend to become Autarchs, and they have already have a slightly different, more insightful mindset to their compatriots within the squad rather than the one imposed on them by the temperament of their chosen aspect.
Path of the Dreamer
A meditative Path where the Eldar learn to try and control their dreams. Since dreams come from the warp there are probably practical purposes to this such as using this to predict the tides of the warp or aid seers in future sight. Often another Eldar will stand vigil as a "Dream Watcher". The Path of the Dreamer also helps to focus the precision of an Eldar's memory and they can take mind altering substances to aid them while doing so. Though to others it seems like they are wasted stoners who do nothing but lay about all day.
Ironically, those lost on the Path of the Dreamer, called the Everdreaming, will have difficulty telling the difference between the past and the present.
Path of Grief
A Path taken when the Eldar remember their fallen (which is really high) and allow themselves to feel grief without risking the attention of She Who Thirsts. The Eldar on this path will sometimes grieve for someone who cannot be allowed to grieve at this time.
Path of the Healer
Opposite to the Path of the Warrior, your basic doctor and/or nurse but are also psykers, though of a very specific power set in that they seem to focus on healing Eldar souls themselves and are heavily tied to Isha. Their mythology being that Asuryan tied locks of Isha's hair into Eldanesh's hair so his descendants could be healed with the Power of Love
Path of the Mariner
Eldar who have taken to serving on vessels of the Eldar fleet (Craftworlds are too large and maneuverable to qualify as capital ships). Unlike the Imperial Navy, which are crewed by press-ganged slave labour bondsmen who are honoured to serve the vessels of the Imperium, the Mariners are eager volunteers who can leave at their discretion.
Path of the Outcast
Not exactly a Path, these are Eldar who have rejected the regimented ways of the Paths and left their Craftworld. Often it's caused by wander lust, rejection of authority, etc. Those on the Path of the Outcast often become Rangers, serving as scouts for Eldar warhosts. In some cases, Eldar who remain on the Path of the Outcast too long end up cutting all ties with the Paths, essentially becoming a full-fledged Dark Eldar.
Path of the Seer
The Path of the Seer is the most treacherous of the Paths, where an Eldar develops their psychic ability. The Eldar are a naturally psychic species, but rarely do they ever learn to develop their powers to the level of Human psykers. Seers are vitally important to the survival of a Craftworld, as they can study the flow of fate to predict what dangers the Craftworld will face. Seers gather together to form Seer Councils, groups which form the leadership of a Craftworld. Special types of Seers exist, such as Bonesingers, who manipulate Wraithbone, the core component of Eldar constructs. Warlocks are those who have previously served as warriors in an aspect of Khaine, and can become some of the most potent battlefield psykers in the galaxy. Those who become lost of the Path of the Seer become Farseers, individuals who can see incredibly far into the future. Eventually, the psychic power within the Farseer will overwhelm their body and turn it to crystal, becoming another node in the Infinity Circuit. Unlike the other paths, those who become Farseers usually chose to become trapped on the Path of the Seer, for the sake of their Craftworld.
Path of Service
Butler, Housemaids Janitor, Valet, general Dogsbody; everybody needs them. Since participation in the Path system is largely voluntary (if you don't like it, leave) Eldar on this path must have a burning desire to get those stubborn stains out.
Either that or they just want see what it feels like to NOT be an arrogantly superior prick for a change and start scrubbing Toilets and washing dishes.
Path of the Warrior
Founded by Asurmen after the Fall of the Eldar, the Path of the Warrior is where an Eldar will study at one of the shrines of the Aspect Warriors, learning all they can about their Shrine's skills. Guardians are not treading the Path of the Warrior, but are civilians taking up arms in reaction to an emergency situation. Those who become lost on the Path of the Warrior become Exarchs, the priests of the Shrine. Being lost on the Path of the Warrior will end in one of three ways: to die in battle, to be sacrificed as the Young King to awaken the Avatar of Khaine, or to become the new host for a Phoenix Lord. Though should an exarch die in battle their personality will live on in their armor. Once donned by another Eldar destined to become an exarch the new personality merges with the personalities already within the armor and new gestalt assumes the name of the original occupant.