Versatility is the racial ability for humans in Earthdawn and it is the most powerful and most complicated racial ability available. In most settings humans represent a relatively simple, baseline character to become familiar with the setting and system. This is not the case in Earthdawn and effective leverage of their Versatility Talent requires a significant degree of system mastery and an unusual level of character planning will also be useful in getting the most out of this unique Talent. The only drawback of Versatility is that heavy dabbling will stunt character advancement.
For those that are not entirely familiar with the system, Versatility allows you to purchase Talents which you may not normally have access to. There are three primary limitations to this: 1) You may have a number of Talents through Versatility up to your Rank in Versatility; 2) You may not acquire a Talent through Versatility which is a Discipline Talent for one of your Disciplines. Though if you acquire an additional Discipline with a Talent that you purchased through Versatility as a Discipline Talent, it will become a Discipline Talent when you achieve the appropriate Circle and free up a Versatility "slot" after the Discipline Talent is raised to the same rating as the Talent gained through Versatility; and 3) All of these Talents must be taught by an adept that knows them (not necessarily as a Discipline Talent) and you must have at least the Circle when your teacher learned it. For example, if the Warrior teaching you Swift Kick learned it at 6th Circle, then you must be at least 6th Circle to learn it and will raise it as a Journeyman Talent, despite that a Warrior can learn it as early as 2nd Circle as a Novice Talent.
What this functionally means is that humans can bypass the traditional structure where every other Namegiver learns Talents: Disciplines. They can cherry pick Talents to suit their character and acquire what may be key Talents without learning additional Disciplines. The human restricted Journeyman Discipline is an apotheosis of this idea: all they have is two Versatility Talents. This Talent is best used in a two different ways: to provide a greater range of abilities (width) or increase effectiveness in a particular field (depth).
By far the most common and intuitive use for Versatility is for additional functionality in a Discipline. This can include a Nethermancer that wants to dabble in being a merchant and the social game, or a Swordmaster that sees themselves as a hard-boiled fantasy detective. This goal is also relatively easy to attain; it involves determining what areas you would like to expand into and what Talents would be most effective for that. It is always worth weighing if it is worth investing the resources for width if it can be accomplished with a skill to the same degree. If you are looking for no more than 4 ranks, then a skill (if available) is going to be a better choice in the long run. The advantages of Talents are long-term and will likely not be fully realized for minor purchase. No matter what your end goal with Versatility is, having a plan is important.
For the aforementioned Nethermancer, that would include Evaluate and Haggle to be a merchant, but the social Talents will require more time. First Impression is always a good place to start, but from there things can get tricky as there are a number of options (Etiquette, Flirting, Impress, Lasting Impression, Seduction, Winning Smile, etc) and may or may not be appropriate for what the goal for that character is; perhaps a skill may be better for some of these Talents. The Swordmaster is in a similar situation as there are a great number of Talents to gather information in different ways, from Astral Sight, to Direction Arrow, to Evidence Analysis and on to Search. As you can see, having a plan is important.
Improving the depth of an adept through Versatility is a trickier proposition and there are two ways of going about it: Find what will make you better at what you are already good at, or find the weaknesses in what you are good at and fill those out. A simple example of getting better at something you are already good at is for every spellcaster: learn the Thread Weaving Talents of the other spellcasters. With Nethermancy, Spirit Hold, Spirit Talk and Summon [Ally Spirits], a human Elementalist could easily fake it as a Nethermancer. Now, there are some caveats to this: despite being explicitly allowed, not all GMs might be a big fan of this plan, and with good reason - it represents an amazing expansion of what you can already do, both width and depth. Within setting, most spellcasters will be hesitant to give up their secrets so easily. To minimize your weaknesses, look at what your Discipline does well, then figure out what it does poorly in that realm. Sky Raiders, despite the use of Fireblood, don't actually have much in the way of defensive Talents. A human Sky Raider might think about Life Check and Temper Self, or even Air Dance for both initiative and potentially another attack (both things they aren't so great at).
Here is an example: Elena, a human Swordmaster, has decided that being a Swordmaster is sweet, but she wants to kick even more ass (also be less in danger of falling unconscious constantly). She has a few problems to tackle, but damage, initiative and toughness are the biggest ones. She decides that Cobra Strike will be her best bet on initiative - she is having a hell of a time against Parry and most of her Swordmaster opponents already have a good initiative, so getting an Excellent result will be difficult, but just beating them shouldn't be that hard. Damage is trickier, but Down Strike and Great Leap will be dependable solutions. She has also seen her sister use Swing Attack and wants in on that - it increases damage and is awesome. For taking additional damage, Wood Skin is attractive, but forethought isn't really her wheelhouse, so she goes with Fireblood.
Hopefully this discussion on Versatility will useful in showing how it can be used (perhaps abused) in any game and new ways to think about what can be accomplished with it. As usual, any questions or additional information is always welcome in the comments.