Prayer Beast
I don't see many of these anymore, but essentially they are a version of the strength pure with lots of prayer as well, although many raise their attack to wield rune weapons, the 2hand seeming to be a favorite choice (because they don't raise defense and therefore cannot wield shield), for armor they wear monk's robes, to increase the time they can use their prayers.
Tip: using Long Range style while fighting something with ranged also raises your defense
Tip: Regardless of your equipment, you should not use many prayers at once, casting the att, str, and def buff, along with item protection, increased healing, and protect against melee will leave even someone with high prayer at 0 points very quickly, also, you should always save a couple points in case you are going to die so you can use protect item
PKing Hotspots
Low Level Wildy (especially near Varrock)
Between level 1-4 wildy just north of Varrock is easily the most crowded spot for PKing, although it is mainly low levels (3-30) a good place to start out, and if you are a higher level you may even see someone you can fight in this area.
This area is a bit safer because only people around your level can attack you here, and it has an easily defined multi, and non-multi combat zone, worlds 1 and 3 are full of people here, but if you choose to PK on this world I recommend you have friends there, because you can get teamed up on by multiple people quite easily.
Mid Level Wildy
The mid level of the wilderness is around 15-25, most people stay between 15 and 20 though (you cannot teleport back to town past level 20 wilderness), there are 2 main areas of interest here.
The Dark Warrior's Fortress is the first, it is full of low level Dark Warrior's which drop black maces, meds, and daggers I think, there is also an air, fire, earth, water, mind, body, and chaos spawn here, it would be a decent place to train, but you would probably get PKed a lot, this is my personal favorite place to PK, as you get levels ranging from 30-100 here, it is about level 15 wildy though, so be wary of people higher level than you, much fighting occurs outside the fortress, but inside the fortress itself is a good place to attack people, as you ca trap them by shutting the doors, the Dark Warrior's Fortress is located north and a bit west of Edgeville.
The Giants area is the other good mid level wildy area, Hill Giants roam around it, making it ok for training as well, although it doesn't get as much PKer traffic as the Dark Warrior's Fortress, it gets a decent amount, and there is almost always a group of like 5-6 pkers there on worlds 1 and 3, the Giants area is located northeast of Varrock, almost as far east as possible, around level 17-18 wildy.
High Level Wildy
Anything above level 20 wildy really is considered high level wildy, you see less single PKers out here, most traveling in parties, also, towards the back people who are 40-50 levels higher than you can attack you, so it is quite dangerous, I generally avoid this area when I'm actually PKing, since you have to run back to level 20 wilderness to teleport and escape, but it is a nice place to do other things besides PKing, there are 2 areas with chaos dwarves, which are around level 56 I believe and have pretty good drops, there is a cut sapphire spawn, 2 rune rocks (think there are 2 at least) and greater demons, along with several other decent item spawns.
PKing Techniques
Solo Techniques:
Hit & Run - Mainly used in the low level wildy near Varrock, this consists of casting a spell or shooting an arrow or two at someone further out in the wildy, then retreating to an area where they can't hit you, not great for killing them, but if you get a nice hit you can waste some of their food.
Bind - Cast bind on your opponent then cast spells at them while they are immobile, if you alternate between Bind and your attack spell on a melee fighter, you can pretty much kill them without being touched, this technique requires quite a bit of nature runes though.
Rushing - This really only works in the low level wildy, and requires you to teleport a lot, have the item protection prayer, and is much easier if you get through the Al Kharid gate free, basically, you run out, with only your weapon, attack someone and fight until you die, casting the item protection beforehand, go to lumbridge still with your weapon, run to Al Kharid, withdraw tele runes from bank, tele to Varrock, run out and attack the same person again, you can also use defensive prayers while fighting, as long as you have enough for item protection when you die, because you can recharge in lumby or varrock
Team Techniques
Waiting - If everyone in your team attacks a target at once, it will almost always run away, a better way to beat them is to have only 1 person attack them, then, when they are almost dead, the rest of your group attacks as well, make sure your opponent is in multi combat when fighting.
Bind - Same as when you are solo, but you have 1 person in the party whose sole job is to bind enemies, while the others attack them, much more effective IMO.
Hiding - Works better in the mid-high level wildy, since in low level wildy you can hide anyway, have 1 person in your party approach an area with a PKer(s), get in a fight, then PM someone in the party to have the others come and help, make sure opponent is in multi combat when you enter fight.