Many thieves enjoy their time on the Disc and never become playerkillers; for others, playerkilling adds a whole new dimension to the Disc. There are some common misconceptions about life as a playerkiller... you will not get attacked or corpse looted by every PK you come across, for example.
The only set rule about when to go PK is that thieves can't make the choice before two days of age. Some players prefer to wait until they have certain skills, others make the choice as soon as possible - and risk becoming 'easy' targets. Numbers are, of course, very useful; but PKs are not NPCs, and there is no substitute for PK experience. Your brain is your most important weapon. Feel free to ask other thieves on the talker, and have a good read of 'help playerkilling'.
Etiquette and Common Sense
It is much easier to get a bad reputation than to shed it. Everyone makes mistakes, but a little common sense goes a long way. Once you are branded a 'git', it will be extremely difficult to lose that black mark - you can expect regular attention from any bored playerkiller as well as possible contracts from the assassins' guild simply because the community at large is attempting to run you out of lives.
Keep a low profile initially - avoid making yourself a target. Get a talker and turn on the 'playerkillers' channel - listen, and you will pick up a lot about the playerkilling community. Avoid talking on the channel until you are confident. Do not announce that you have just become a playerkiller unless you want to suffer your first PK death within the next few minutes.
You have a 'hide' command. Use it, especially when idling in a public place. Random attacks and kills aren't an everyday event, but they can and will happen to you. Deal with it. Respond with abuse etc, and deaths will become much more frequent. If you want to talk to the aggressor, be polite.
The Thieves' Guild should have honour - try and maintain it. Using your skills to avoid death (not just fighting skills) will gain you a lot more respect than running to a safe room - this can often make a situation worse. Personally, I'd prefer to meet Death than hide in Brother David's.
Don't taunt aggressors if you manage to evade them. Chances are, they will come back more determined, perhaps with several friends.
PKs are (with one or two exceptions) more intelligent than NPCs. Consider one, and he'll wonder if you are about to attack. If a PK spots you peeking or casing, he will wonder if you're after his inventory. Players' responses vary widely but can and will include attacking you in self defence - be aware of the potential consequences of your actions.
If you random someone, bear in mind that they may not be too happy about it and could come after you at a later date, or set their friends on you. Also remember that the five day old assassin you kill could very well have a three-hundred day old alt that will suddenly take a very mysterious interest in seeing you dead.
Looting from another player's corpse is generally considered to be a much harsher action than merely killing them. You should be well aware that doing this indiscriminately is an excellent way to gain the kind of reputation mentioned at the start of this section. This counts double for looting from a dead PK you didn't actually kill yourself.
Remember, behind every other PK there is a person on a computer. Treat other people as you would wish to be treated yourself - consider how your actions might look from the other side.
You're a thief, you're a playerkiller, and naturally you want to steal from other players. Stealing from a player is quite different to stealing from an NPC. Players often carry more interesting - or valuable - items, but many have decent perception bonuses. Like NPCs, PKs may attempt to mash you should you fail. You also have the added risk of wards. At present, items can be warded with various rituals currently available to priests. Some are annoying, some are painful, and some are actually beneficial to the thief (depending on the intelligence of your victim).
A 'clean steal' is when a thief takes an item from a victim who has absolutely no idea as to the thief's identity. If you aren't hiding when you make the steal, it might give the game away; likewise if your victim sees you in several rooms and then suddenly isn't holding the weapon he's been mashing NPCs with. Bragging about steals on the talker is not advised - as well as looking like a git, word might get back to your victim. If you steal in AM, you leave a receipt, which, when handed in at the guild, informs the victim of your identity - making it an unclean steal. Bear in mind when filling your quota that playerkillers do not instantly hand in their receipts - 'review receipts' is a useful command. Selling items back to the victim is an interesting option, but proceed with caution, perhaps using an intermediary.
PK stealing can be fun and exhilarating, but people don't like to be stolen from, and you have to be prepared to accept the consequences of both success and failure.
PK fighting can be great fun. It can include mass brawls, friendly spars, and even an organised league. Brawls can be arranged on the talker; they also occur spontaneously. Spars are a good way of learning how to fight - the more you practice, the more you should learn. If you spar with someone you don't know, make sure you agree certain rules beforehand - whether stealing is allowed, if it's to wimpy or death, in one room or a set area etc. A quick discussion beforehand can avoid a great deal of aggravation later. Try to learn from your fights - watch what your opponent does, how he counters your skills/attacks, and try to think of ways to counter his. There is much more to fighting other PKs than hitting backstab and waiting to see what happens - experiment!
Commands, Help and Support
Killers here, qwho killers, qwho killers&assassins etc are useful commands. At present, there isn't an 'enemies' list, so if you fall out with someone or want to avoid/kill/steal from them, adding them to your 'friends' list may be useful - possibly with a tag to remind you what needs to be done.
Random kills do happen, but if you find that you are being picked on repeatedly or harassed by the same person, there are people out there who can help you. Guild monitors are there for your support; don't be afraid to approach them if you need help. Having said that, be sure to give the full and complete story. Leaving out the part where you stole the other guy's deluded, bonded weapon and buried it is generally not received well.