When it comes to PVP theres three things to take into consideration, defense, damage and timing.
At the beginning of the fight you would buff up and use your defenses early while having damage increasing accessories, once your buffs wear off you would switch back to defensive accessories to tank more damage.
Swapping accessories back and forth is key to winning fights, and is definitely something you should practise and master.
What items to get and whatnot really depends on your economy, because items on this server are far from being cheap.
Your first prior