This post is about Attributes, a subsection of skills
Skill Advancement: Skills are increased as they are used. Using a skill has a chance to increase it by a small amount, and when a certain amount of this "skill xp" has been gained, you gain a skill level. The skill xp requirements are semi-exponential, meaning that eventually you will reach a soft cap on skill increases, but that there is no firm hard cap (or if there is one, it is so far beyond normal playtime that it isn't practical to reach).
Skill Transfer: I am debating whether or not to allow a player to imprint their skill xp onto an item that would allow it to be transfered to another player. This would be a 1 for 1 trade of skill xp (so imprinting lvl 10-1 of your skill drops you to lvl 1, but it may not be enough to give even a single level to someone who has lvl 50), so I don't think it can be abused much, but would allow players to pay others in order to skip a hard part of levelling their skill. It would also allow players to sell the skills they are not using if they wish. This idea comes from Entropia Universe, where it works very well. The difference would be that the imprint device would be player made, instead of sold by the game itself. I think I would limit this so attributes could not be imprinted.
Attributes: Attributes are the vital statistics of your character. They are used as modifiers towards your skills, and act like skills themselves in many regards. Any time you utilize a skill with an associate attribute, there is a chance for it to increase (as if you had used it as a skill). Attribute increases will seem fewer and further between than skill increases, but they should increase fairly quickly, as they cover a lot of skills.
[Skills mentioned are just examples, not a complete list of what those attributes effect]
Strength: Your physical force. Used in skills that require brute force, like attacks with blunt weapons, and increases damage with physical attacks.
Dexterity: Your agility and fine motor skills. Used in skills that require finesse, like ranged attacks, attacks with some slashing or piercing weapons (like a rapier). Determines your critical hit chance with physical attacks.
Stamina: Your health and physical resilience. Used to determine your health, damage resistance, and skill in using heavy armors. Increases your chance to resist bonus damage from critical hits.
Intelligence: Your mental power. Used in skills that require smarts or brainpower, like many forms of magic. Increases effects with magical attacks.
Insight: How well you understand things and your "gut" feeling. Used in crafting experimentation, and in critical hit chance (finding a weak spot) for magical attacks. Increases accuracy with magical attacks
Charisma: How well you relate to others and your force of personality. Primary attribute in the charm school of magic, increases your magical defenses including magical critical hit resistance. Determines many interactions with workers.
Ideally these attributes will be fairly evenly split through the skills so that no one attribute is more useful than the others. That said, Stamina will be a preferred stat for many adventurers and Charisma for many crafters simply because they determine health and worker interaction, two of the primary resources of those two worlds.