Denying Experience

Denying creep (minions) is not possible in League of Legends. Mostly this is because it is weird. Who goes around killing their own teammates? No one. It's cause it's weird.

Anyway. There are plenty of ways to get ahead in the experience column.

1. The first method is simple. I like to call it Creep Blocking. basically it is when you force enemy champions away from the battling creep. This is easily accomplished as a ranged hero because you can simply attack the enemy and harass them until they run away.
2. The next method is not really a method at all. The strategy is called last hitting. As you may (or may not) know. You only gain gold on creep kills if you score the killing blow. To last hit effectively you want to sit back waiting for a minion's health to drop to a low enough level before you stab or shoot it to kill it. This gives you the gold you want. Doing this effectively can result in a lot of extra gold on your side.
3. Sometimes it is best not to kill minions. Usually this occurs at low levels. Say the enemy has not shown up to the lane yet. in order to deny them some experience you simply sit around and only score last hits. This will result in a few of your minions dying. If they die before an enemy champion shows up then they are out that experience and your already ahead of them.
4. After you have ganked an enemy lane or simply gotten rid of the enemies in the lane and you have some time on your hands. You should attempt to push to the enemies tower. This does two things. First, the minions die to the tower and deny the enemy both gold and XP. Second, you can deal significant damage to the enemy tower.

While none of these methods will result in a huge difference in level or XP they can result in enough to change a fight. An extra level means one more ability and extra stats. Usually (but not always) you will find that the higher level team has a higher KD and, more often than not, ends up winning the game.

Keep this in mind when you play a game: Harass often and harass with force. An enemy that is always on the defensive is a broken enemy.

Also, I just found this LoL Rap. I find it... interesting.