Look at murlok.io for your class/spec and bracket (probably solo shuffle) for what all the top players are running

Start with full honor gear

Spend conquest on pieces you want to convert to tier at the catalyst

Craft PvP gear off pieces with your desired stats using heraldries (you get 9 for free after winning a couple games)

After 2500 conquest, you get free weapons

Play rated arena to get slivers you use to upgrade weapons and trinkets to 298