When I used to run my old guild, I personally trained our Night Elf hunters to survive in the dangerous world of our PVP server. When they reached the ripe old age of level 30, I would bring them deep into the jungles of Stranglethorn for survival training. After a lot of time out in the wild, I learned well how to evade and escape even the strongest enemies. So I used to pass on these skills through a game of hide and seek.
The key to evasion as an elf is their racial ability, Shadowmeld. I personally see this as one of the most useful racial abilities. If you are an elf, it will be in your general skills tab in the spellbook. This ability allows any class to stealth as long as they are not moving. It has a lot of uses, but for our purposes, I will be teaching you how to use this to escape enemies of any level who attack you.
I'm sure you have had plenty of times when you are fighting enemies out in the wild and suddenly out comes a level 70 horde with full epic armor and nothing better to do than bully and kill poor helpless alliance. You obviously have no hope of killing him so you have to try to escape somehow, but he's got a mount and you don't. It's hopeless right? Not at all. You just need to get good at hiding.
The first thing you need to know about any stealth is that it doesn't make you completely invisible to all enemies. If someone your level gets within a certain radius of you, they will hear the stealth noise and see a shadow of you standing there. If someone is a few levels higher than you, they will see you more clearly and from further away. So if you meld in plain sight, a 70 will see you just fine and get a good laugh before killing you. BUT if you hide well enough, they can't see you no matter what.
If you jump into grass, or under a bush, your body is hidden by the leaves. Even laying down in front of mottled coloration, in a shadow, or a dip in the ground can hide your form. You want to be either in front of or behind something with lines that will hide the outline of your body that can be seen when you meld. Once you use shadowmeld, be sure to lay down (type /lay) or sit down (Press the x key) as this will make you much harder to see. When you are shorter, there is less chance you will stand out. Practice hiding while not melded and try to make it so you can't be seen. Then work on running and ducking into cover. When you get this down well, you can pick out a good hiding spot and duck into it at a full run. You want to be good enough at this to escape from attackers in hot pursuit. I used to play hide and seek with guildies to teach them to duck quickly under cover.
When you are attacked by an enemy, it helps to put a mark on his head so you can watch him on radar without turning around. Fire off a concussive shot at him to slow him down. If he is close, use a scatter shot to put some distance. As soon as you are out of range of his attacks, pop on aspect of the cheetah and book it. If you aggro or the enemy gets close again, switch quickly to aspect of the monkey so you don't get stunned and caught.
When he follows in line with you and you have a second or two between you, jump into the air and drop a freezing trap in mid air. If an enemy sees you stoop down, they will know you set the trap, but in mid jump they won't notice. Try to lead them into the trap and watch their picture at the top of the screen to see if they are frozen.
As soon as you get around a hill, behind a tree, or any chance where the enemy may not directly see where you are, jump under cover. You will still be in combat so immediately feign death to slip out of combat. Then quickly meld and lay down.
The enemy will probably hear your stealth if he gets close, but if you're well covered, he won't be able to see you. If he saw where you disappeared into, he may be able to use an AOE attack to flush you out and bring you out of stealth. But if you pulled it off when he couldn't see you, he won't know where to look. When he mounts up and runs off, go back to having fun but keep an eye out for him.