To jungle as Alistar effectively, you need Pulverize as your first skill because it does the most AOE damage & CC to the creeps. Start your jungling path at the wolf, then proceed to Blue. Ideally, you want to start ganking @ level 2 from behind with headbutt and follow by pulverice, preferably bot lane or top if the enemy overextends even slightly. If the enemy plays turtle you should proceed to clear the rest of the jungle as fast as you can and look for ganking opportunity @ level 4. If you aren't ganking, the second skill you need to learn is Triumpant roar, this skill will increase your sustain in the jungle tremendously. The third skill can be either head butt or pulverice depending on how fast you want to start ganking.
Jungling Route = Wolf -> Blue -> Gank Top Or Bot (Situational but high recommended) -> Wraith -> Red -> Golem -> Wraith
Alistar Pre Level 6 -> After the big nerf on head butt range, Alistar no longer poses the scary "backside" ganking threat as it used to. But he can still deal severe punishment to unsuspecting player who overextends greatly and have poor map awareness due to lack of wards. Gank from behind with headbutt (W), walk towards the dazzled enemy and pulverice (Q) for maximum time of CC. Watch your enemy destroyed by your carry and type /l to laugh.
Alistar Post Level 6 ->The same as pre level 6 except that now you have unbreakable will, and you can now dive the enemy with low health(<50%) under tower from anywhere to secure kill for your carry.
Team fight -> You play as a protector of your carry and also the one who initiates on the enemy team carry(who is fed). Do not waste your combo on enemy's tank or support unless their ad/ap carries are busy farming far away.
3 absolutely important Alistar combo moves you must learn in order to play Alistar well.
Summoner spells are Flash & Smite
My favorite items for jungle Alistar in season 3 are as follow:
Machete, Boot Of mobility, Philostones, Sheen, Spirit Of Ancient Golem, Trinity Force & Frozen Heart.
Alistar Jungle Masteries, I prefer attack damage for easier time on jungling.
Runes : 9 X Greater Seal Of Armor, 9 X Greater Seal Of MR, 9 Greater Mark of scaling attack, 3 X Q of Attack Damage.