The player vs. player realm is a special, more cutthroat type of realm where players compete against both monsters and each other to progress through the game. This experience has its ups and downs. Sometimes, you successfully attack other players or win large battles. Other times, you're on the losing end where you're defeated and driven away. This gameplay type isn't for everyone. If you wish to fight mostly monsters, with some player vs. player combat only at your choosing, you should try a regular, non-PvP realm. You should know what you're getting into and be prepared for the consequences. If you find this gameplay type is not for you, it is recommended that you create a character on a normal realm (non-PvP).

Many players prefer the player vs. player realms for several reasons:

There is the excitement of facing real people in addition to computer-controlled monsters.

On normal realms, when a player of the opposite faction offends you, there is no real counter.
On PvP servers, however, you can kill them!

Level Difference:

It is possible to kill players much higher level than you. You can hit them. There are certain class match-ups that will work in your favor despite the level difference. It's much easier killing a higher-level player than a high-level monster. One of the main differences between different level characters is damage output. Thus, many lower-level players can take down a single higher-level player with their combined damage output.

Frequency of PvP Combat:

The frequency with which hostile players of your level attack you decreases in higher-level regions. In low-level contested zones (level 20 to 30ish zones), players are usually new to PvPing and will want to attack any enemy they see just to experience PvP and without any apparent reason. In higher-level zones, players are used to it already, and PvP fights will usually take longer. It's harder to catch runners, so enemy players will often mind their own business and leave you alone. So don't get scared if you're getting killed too much in your first contested areas; it gets easier as you level up.

Classes:

Try to learn how your class fares against other classes. That way you will know whether you should fight or flee when you spot the enemy. You can always try trial-and-error to begin with.

Races:

Try to learn the enemies' racial abilities. Undead, for example, have an ability that helps counter Fear.

Pay Attention:

Playing on a PvP server means paying attention. Look over your shoulder at almost all times. Know that your quest plans could change any moment and turn into a battle with the enemy faction. If you're not ready for this, consider a PVE server instead of or in addition to PVP. It's not for everyone, but you'll find that most people that play and enjoy a PVP server love the exhilaration of never being safe. It takes skill, it takes patience, and it requires that you keep up with strategies. It might mean more reading and studying than the PVE servers, but if you're reading this, chances are you're up for it. Good luck.

Adventure in Groups:

It's a lot safer to adventure with a full party. That way, if one or two enemy players attack, you'll have a better chance of surviving. Solo players are the most at risk and should be prepared to die more depending on their class, skill level, and items. A bunch of low-level players can take out a higher-level player with enough numbers. So if there is a high-level enemy killing many people in your region, rally defenders by using the LocalDefense channel and by using the /who command to check for other players around. Get together with other players who are getting killed by the same enemy you are, party with them, get yourselves organized together, and hunt him down.

Stay Together:

Work with your group. Pay attention to who's attacking what target and stay together. Most groups are wiped out because they didn't work together on a target or because they spread out. Staying together, however, doesn't mean bunching together. Stay within range of helping each other. If you bunch, you'll be susceptible to area affects. It takes practice, but it's worth working on. Sometimes it's too easy to want to leave your group to chase down that almost dead enemy. Consider that you can be vulnerable as you leave your group and you can weaken them by leaving them a player short. Some teams actually work on this as a strategy, pulling apart strong groups or baiting them into ambushes. You're only as good as your weakest link.

Run Away vs. Stay and Fight:

If you think you cannot win, run away. If you know you can't get away, you can just stand there and die. If you don't fight back at all, it takes some satisfaction away from the person killing you.

However, for other players, it may actually encourage them to attack you more because of your cowardice. You shouldn't bother running away if you know you can't escape. Some players recommend fighting bravely to your death instead of running away. There's no telling how the enemy player will react to your choice. It's a grab bag of possibilities.

It's almost always best to get the jump on the enemy. Every class in the game has an opener ability that will give you an advantage if you're the one who strikes first. Attacking first also gives you the element of surprise. So if you get jumped, sometimes you can choose to run away or "pretend" you're running, hide, sneak back, and jump on him.

Stay off the Roads:

If you want to avoid the enemy, stay off well-traveled roads. Take paths that players wouldn't normally take. You may still run into enemy players, but the chances are less. This is especially important in enemy territory.

Distances:

Standing right next to that enemy warrior isn't such a good idea. Neither is running away and turning your back to that Hunter that can shoot you in the back from far away. Distance and direction are important in different ways for each class. Learn your ideal distances and learn to move. Many players from older MMOs are set in their ways and stand still to fight. It's a learned behavior that might get you killed. Though you might not be able to move while casting some spells or using some abilities, there are many instant or non-timer abilities that can be performed as you move and jump.

Always watch your health and mana:

In heavily contested territories, you should be much more careful about your hit points and mana. There is no telling when an enemy might surprise you, so it's much better to always stay high on hit points and mana. Eat, drink, or bandage after every kill.

Ganking:

Ganking can mean being killed while fighting a monster or killing another player while they are fighting a monster. You WILL be ganked on a regular basis. Watch out for other players while fighting. Often, players will be consumed with their current fight and won't notice the enemy attacking from behind. Don't let your guard down.

Harassment:

You may sometimes come across an enemy player that continually stalks you. Be aware of the PvP policy concerning such harassment here. You have several in-game options available to you for dealing with such a situation:
Continue to Fight - You can keep trying to get away and return to fight again.
Leave - go find another area or zone to play in. There are usually multiple options. Consult the region levels or quest levels page.
Get Help! - Use your guild or general chat channels to get reinforcements to kill the attacking enemy players. This can work sometimes but will not always work. You might have to deal with this situation on your own. If there are players in your party you can also organize them to defend yourself.

Reputation:

Be warned, constantly harassing and killing players over and over, attacking them when they are fighting monsters, and camping their corspes may hurt your reputation. Players may band together and hunt you down with extreme prejudice.

Celebrating your Kill:

Many people use emotes on the enemy corpse to celebrate their kill. If the enemy player has not released their body then they can also see those. So, usually players hit release as soon as possible to avoid being "emoted on."