When making a skill check, roll a d10, add the number of skill points you've invested in the skill, and compare to a DC. The DC for a skill check ranges from 3, for almost trivial actions, to 15, for almost superhuman actions. Unlike most other actions, a roll of 1 doesn't necessarily fail, and a roll of 10 doesn't necessarily succeed.
Acrobatics: Do stunts, like walking on tightropes, sliding down bannisters, or jumping through hoops.
Arcana: Understand magical effects.
Bluff: Tell lies by rolling equal to or higher than any observer’s Insight. You can also be Frightening with a Frightening value equal to your Bluff check -10 as a standard action, affecting any number of creatures within 20', or any one creature who can hear you.
Diplomacy: Hit things off right, or persuade someone who's ambivalent.
Disguise: Conceal your appearance or that of another to seem like a different creature of similar size and shape. Tricks people unless they roll higher Insight than your Disguise roll.
History: Remember past events, and the locations thereof.
Insight: Detect lies by rolling higher than the target's Bluff. Detect disguises by rolling higher than the target's Disguise. Either of these things is a minor action, but can only be attempted once per statement or disguise.
Items: Identify items, or repair them.
Legerdemain: Conceal actions with an effective Stealth value equal to one third of your roll. cheap actions have no penalty, immediate actions and minor actions have a -3 penalty, move actions have a -9 penalty, and standard actions have a -15 penalty.
Nature: Identify plants and animals, predict the weather, forage for food.
Scripts: Understand ancient or damaged writings. Make forgeries, which can only be seen as such with an equal or higher Scripts check.
Strongman: Break iron bars, smash doors, climb.