"Safing" and Food Use
It is perfectly acceptable to 'safe' to over 70% HP in members world. Any higher and people get annoyed and will most likely stop fighting you. In contrast, you shouldn't safe to more than 35 in F2P EXCEPT in multicombat. Be aware of what the max hit with an R2H at your combat level is. Max is 33 in F2P, at 99, potted, and ultimate strength prayer.
On the topic of food, bring Tuna Potatoes and at least 2 Sara Brews- If your HP is dangerously low, there is no lag from eating a potato to drinking your brew, thus giving you 38HP quite instantly.
Keep in mind you then have to pot back up.
Prayer
Protection:
If the foe is ranging or maging, it is perfectly acceptable to use Protect from Melee to avoid a cheap AGS KO. Otherwise, protection prayers should only be used if the foe uses them first. This is part of PKing's "code of honor", which really does serve to make everyone happier. If you pray, they pray, and then neither of you can get the kill and you both just waste your supplies.
Other Overheads:
Smite - Good. If someone asks you to take it off, put on a protection prayer. Nothing is wrong with Smite.
Redemption - Is very rarely useful. Just sits there draining your prayer. The bigger problem is that upon healing you, it drops your prayers, including protect item.
Retribution - Pointless. Avoid this unless your foe is Dharoking and you think you can get back to loot his Death site quickly.
Boosters, etc:
Protect Item - If you make a deal with your foe to leave protect item off, do so. Otherwise, keep it on at all times. Yes, your foe may also break the arrangement and use protect item, but it should usually not be a big deal on PvP worlds. From what I can tell, you won't be able to know for sure whether they saved that top item or not.
Protect Item Part 2 - If your foe has a godsword and you have a godsword and he declares "no prot item", ignore his ass, leave it on, and say "kk". I don't care if it's a lie, honestly, because he DOES have protect item on.
Rapid Heal - Has saved me at 1hp in 3 years of PKing a total of one time. May possibly be more helpful if combined with a regen bracelet. Not worth relying on, but the drain rate is so low it's worth using.
Boosting Prayers - Worthless. Never use them.
JK! Boosting prayers are the most important prayers in PKing. You should always use the best available to you. If you are a regular player, I would advise unlocking piety. Piety/Eagle Eye/Whateverthemagiconeis should be used at almost all times. Remember that you can only have prayers from a single combat class at once, and only one prayer per skill. Pures usually avoid piety and chivalry as the quest requires 60 (?) defence.
Strategy
Now, you can't just throw all of the above together and wish yourself good luck. You don't even have equipment yet.
Honestly, the strategy is the most important part, but no one can help you with that. You have to develop that on your own.
This video's got a little bit of all the best "maxed" PKing methods. Whip+AGS, MSB+AGS, Dharok's+AGS, etc. The AGS can always be replaced by a different KO method, like the DDS, but remember that you'll have to wait for significantly lower HP to start your KO Swing- And most players don't let their HP down that far, anymore.
http://www.youtube.com/watch?v=6lA3ZUpqCsI
If you look around, I'm sure you can find a video for almost every method/levels/tactics possible.
This topic will be expanded based on further suggestions. I will also expand it significantly once I've had time to acclimate myself to the mechanics of the as of yet unreleased PK worlds.


















