Gear: weapon first, then your main stat
Why
While leveling, you'll replace gear constantly. A better weapon is the biggest upgrade you can get; everything else is small.
Do this
Upgrade your weapon whenever you can. For other slots, pick the item with more of your class's main stat (your class guide lists it).
Less waiting, more playing: two other stats cut the time you spend sitting and eating. Stamina gives you more health, so you can do more fights before resting. Spirit makes your health and mana come back faster. If two items look about the same, take the one with these.
What do armor types mean?
There are four armor types: cloth (lightest), leather, mail, and plate (heaviest). Your class can wear its own type and every lighter one, so a class that wears plate can wear anything, and a leather class can also wear cloth. There's no penalty for wearing a lighter type, so a great cloth item beats a bad leather one. Hover over an item and hold Shift to compare it with what you're wearing.
What do item colors mean?
Gray: junk, sell it. White: basic. Green: good. Blue: great. Purple: excellent, usually from raids.