I left this for last because some people will have an issue with this: protect your np's with /town. Why? If you spend any time in CZ you will realize:
if you are facing a cheater (e.g. arrow shower hacker), the odds are heavily against you, and you're better off towning
there will always be players who are much higher level and/or better equipped.

PvP FAQ

What is the minimum equipment (bow, armor) I need for PvP?

What I recommend:
+7/70 iron bow (ap 119)
+6 chitin bow (ap 111)
+6 enion bow (ap 111)
+7/70 iron xbow (ap 110)
+8/80 horn xbow (ap 109)

goblin pauldron for the 16/16/16 resistances
paper archers: +7/12 plate pads, helm, boots, and gauntlets. Or +8/15 half-plate. I'd go with +8/15 half-plate, as you'd get 12 more dex at a cost of 13 defense. If you're paper, your defense is going to suck anyway.

82 hp archers: +7/12 full plate pads, helm, boots, and gauntlets. Get +6/10 or +7/12 chitin gauntlets if you can

90 hp archers: +6/10 chitin pads, helm, boots, and gauntlets. Get +7/12 chitin if you can. You can also wear shell helm, boots, and gauntlets, but you don't bother unless they are +6/10

The most important item is your bow. Focus on getting a good bow over armor.

Do I need a dagger defense helm?
No.

For the non-archer classes, dagger defense is highly recommended. But as an archer, you have the advantage of ranged attack, LF, and MH. If a sin is giving you trouble, spam MH and 720s, and LF until you reach a pack of blue dots. I've noticed that 80% of the time, if I pass another non-rogue character of the same race, the sin will switch to target that other character. Why? Fleeing rogues are a pain to finish off. And any experienced sin fighting you will know this. And if you use a dagger defense helm, you'll be giving up, say, +12 dex, which is about 48+ attack with master. If you're getting spanked by sins, you're probably not making good use of your bow's range.

Which potions should I use?

Don't use anything less than 720 hp pots. The 360 hp pots won't cut it. The 960 mp pots should work fine, and they are much less expensive compared to soul pots. I generally carry 30 720's, 60 960 mp pots, 5 cure curse pots, and 20 blood of wolf.

Best Uniques

Below are the uniques I recommend for archers. You'll notice that I left out Iron Necklace and Iron Belt. Those are awesome for sins, but archers should focus on attack over defense as they have ranged attack