In the scenario where you are not leashing for your jungler get to wave first and auto the three melee minions. You can also choose to auto one ranged minion in q death range so you can get free four stacks level 1. Your damage when you reach max stacks will be higher than most other champions. Champions you should watch out for early game are: Sett, Shen, Tahm Kench and Trundle. They will out damage you almost all the time. If lane state is even look to get priority if you can. Since Irelia can push in waves really fast, clear the first two waves of minions then look for a gank mid or you can also reset and come back to wave with an extra item. The wave will push back and your enemy laner will be scared to fight since you have a long sword with Doran's blade or Corrupting Potion. A second option you can do is stack three minion waves if you can then push in when your jungler is getting the scuttle crab. The enemy laner will be unable to react because they will be missing a lot of farm.
In the scenario where you have to leash your jungler, know that you will be playing weakside. The wave will automatically push towards you since the enemy laner is most likely already in lane when you arrive. Avoid losing health points as much as possible so you don't get dove around levels two or three. It is ok to miss some farm as long as you are getting the experience points. If the enemy team does end up trying to dive you it's OUTPLAY time. If they have crowd control abilities reactively use your w when they use it on you. This will minimize the damage output they have significantly. While charging aim at the minion wave so the minions are at q death health. If there are minions you can q to try reaching there as soon as the enemies have turret aggro. This will maximize the amount of damage the turret does to the enemies. at levels two to three it should take only three to four turret shots to kill an enemy, and that's if they're at full health. Look to get your stun on the enemy champion that is taking turret aggro.

Look for areas where you can get lots of kills. This is when you start to power spike. Goredrinker allows you to be a little reckless with your HP since it heals so much. You can look for dives but, make sure you coordinate with your team. If you guys properly share turret aggro. You always want to be shoving in the side lanes so the enemy side laner has to react. If no one is there to take the wave you can keep pushing and get towers. If they engage on your team teleport immediately if it is a good fight. YOU will be the one to determine if it is a good fight.

This is the phase where you have to be the most careful. This is because your death timer wilil be around 40 to 50 seconds. If you die, then the opposing team gets a free 4v5. If you are split pushing, there are certain criteria you need to know before you get into the side lane: 1. Do you beat the enemy side laners in a 1v1? 2. Is there an objective on the other side of the map? 3. Do you have teleport up? These are all essential to having a safe split push. When there is no one on the map make sure to back up into a safe area. When you can place a ward in an area that will detect anyone rotating to your lane. In a team fight, aim for the squishiest member of the opposite team. It is usually the AD Carry but, the meta is changing so there might be 2 supports or a AP Carry. When you do kill their carry, you should be able to kill the rest of their team with Conquerer healing and Goredrinker Healing.