In F2P pking, most people at higher levels do no armor fighting, or just wear monk robes, so I will give you 2 set-ups to use.
Armor fights:
Armor:
Rune Plate
Rune legs
Safety boots + gloves (found in those places south of Edgeville)
Ammy of Power
Rune full helm
Rune scim
Rune kite/Rune zerker (from FoG)
Inventory:
1-2 Strength potion (4)
Varrock teleport runes, if you arent comfortable yet
Green Drag top (mages)
Rune 2h (for a the knockout)
Swordfish
No-Armors:
while it varies, you would often see this (though maybe somebody could correct me)
Armor:
Monk robe top + bottom
Safety boots + gloves (found in those places south of Edgeville)
Ammy of Power
Rune full helm
Rune scim
Inventory:
1-2 Strength potion (4)
Varrock teleport runes, if you arent comfortable yet
GRAVITE 2H
Swordfish
--
I am fairly certain that rune armor would protect over a gravite weapon, which is why you wouldn't want to pk with it while having armor.
As for stats, keep your 60 Attack and Defense and get Strength up. I would say atleast 80-85. If you have the money, try to get 85 mage for teleblock. It could come in handy.
If you want practice, or see how you fair against others your level, try going to Clan wars SAFE FFA, or Duel Arena.