I like WotC's DMG2 format, but it could be simplified. A lot depends on how much you want to leave up to the DM, and how much you want to tweak the rules. The example below takes out stuff that's already accounted for (Attack Focus & Alertness feats; moved Run feat to Speed line; a symbol denoting a feat would be helpful).
ADVANCED DIRE WOLF CR 4
N Large Animal
Init +2; Senses Low-light vision, scent, Listen +7, Spot +7
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AC 14, touch 11, flat-footed 12
Hit Dice 9 (67 hp)
Fort +9, Ref +8, Will +7
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Speed 50 ft. (10 squares); Run
Melee Bite +14 melee (2d6+11); Base Atk +6/+1; Grp +18
Space 10 ft./5 ft.
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Str+9, Dex +2, Con +3, Int -5, Wis +1
Skills Hide +1, Move Silently +5, Survival +3 (track +7)
Trip (Ex): A dire wolf that hits with a bite attack can attempt to trip its opponent (+13 check modifier) as a free action without making a touch attack or provoking an attack of opportunity. If the attempt fails, the opponent cannot react to trip the dire wolf.