There are instances in World of Warcraft, especially for those on PvP servers when you simply need to run away. If you are encountered by an opponent that you simply cannot beat, run away. Your only other option is to stand by and be killed.
Some people choose to simply wait and accept their fate, but this might even draw on more attacks from those that find your cowardice amusing. You are given the ultimate choice as to whether your situation is best served by running or fighting, but always be aware that a more powerful opponent will not necessarily go easier on you.
If you have no choice but to fight, you might as well use the techniques you innately have to land what little damage you can. Use your surprise attacks or run away and then return in a flash and surprise an enemy. Landing some small amount of damage will at least gain you some respect if running away is absolutely not possible in your situation.
When you make the decision to start a character on a PvP server, there are a few different aspects to the way things work for you to consider. First off, every zone in the game is now fractioned off. If you happen to wander into a contested zone where the opposing faction has any forces, you can quickly and ceremoniously be killed. In red zones, your enemies can attack you but you cannot attack them until they attack you. In the green zones, you are given initiative.
It does not always mean, just because a player is of a higher level than you, that you cannot defeat them. In some instances, your class might be a good match against theirs. Killing high level players is infinitely easier than high level monsters for this very reason. If a low level player has high damage inflicting attacks and numerous drain and bleed attacks, they could probably kill another player of a significantly higher level.
The lower level PvP zones are often full of attacks, if only because players are just getting acclimated to PvP and are interested in seeing what they can do. In the higher level regions however, players hold back their killing for when it really matters, not wanting to risk being killed. If you decide to run, it’s a lot of work and possibly quite dangerous to chase after, so most enemies will just leave you be.
Different classes and races do differently against each other. By learning the differences between a mage and a rogue or any other class, you will know more readily when you encounter an enemy whether or not they are someone you can fight and possibly defeat. Similarly, some races have certain abilities that fare well against other races.
If you do decide to run though, there are some tricks to getting away that you should keep handy to make your escape a little easier. First off, keep certain items on hand for fleeing. Potions of swiftness are especially useful for these situations, cranking up your speed for a few seconds. There are items as well, such as the Nifty Stopwatch that will perform the same buffs and increase your speed.
The world is full of random objects. Use some of them to hide. Find a good tree or a mountain or a cliff side and dive for it. If you can get out of site, you might be able to elude your hunter for long enough to get away.
Be unexpected and run in strange patterns. Never run in a straight line because they can just follow you at the same or faster speed. Zigzag, jump, find rocks, and get away in the most creative fashion possible.