I go different from any Alistar build I've seen and take Clarity. This will give you infinite sustain. by the time this is needed you and your lane partner should have an easy at least one kill. When they come back the will see you are out of mana and try to nuke you with no fight, this is when you catch them off guard and cast Clarity, you can then knock up and headbutt any way you want but this will usually result in st least 1 kill if your partner is in lane. I take ignite as a just in case for champions such as Ezreal who will use his flash to get away but with ignite you will usually take him out if your lane partner cant and get some gold build-up.

Do Not Get Any Farm. You will most likely always be laning with an ad carry and he needs the farm. As Alistar you can simply cast your heal and do damage to minions while not stealing any farm. Simply stand there, heal your ad carry and take some damage and you will get enough money racking up assists.

early lane its all about the cc. You will most likely be with an ad carry, so you have any stun or slow on an enemy and he will be nuked. and in case the enemy team has a jungler, your headbutt can keep him away from your carry and maybe keep you both alive. Early, give your lane partner all the farm and get them fed. A fed ad carry plus an assist fed Alistar will be almost impossible to beat late game. In any team fight get close to any champ that melts, and knock him up because this will keep a lot of damage off the rest of your team. If your team wants to dive just pop your ult and tank the turret and keep all the damage away from the rest of your team