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 half your Bluff check as a standard action, affecting any number of creatures within 8 meters, or any one creature who can hear you. If multiple creatures attempt bluffs to scare against the same target, that target is only affected by the highest roll of any such creature in the time since its last turn.
Diplomacy: Hit things off right, or persuade someone who's ambivalent.
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. Climbing at half your non-run land speed is DC 5 for surfaces with consistent footholds, or DC 9 without. Climbing at full speed increases the DC by 3. Climbing while running increases the DC by 3.