Below I have made a short list of things you should prioritize in order to reach ilvl 7500 as quickly as possible when you hit lvl 70.
Below level 70
1. Obtain an Epic Companion from Auction House and fill other slots with Rares. Buy or Refine Runestones to Rank 7+ and buy ilvl 400+ Companion Gear for the Companions that you usually summon (Rarity of all Companions effects your item level, however only summoned Companion needs Runestones and gear) (companion rank does not effect ilvl)
2. Obtain an Epic mount if possible and fill other slots with Rares (or at least Uncommon if you really are low on AD). Fill all Insignia slots with Rares or Epics (all mounts and Insignias effect item level)
3. Buy Dragon Bone armor from AH if you’ve got the extra AD laying around (Small chance to drop from Dragon Raids). This gear levels with you all the way to level 70.
1. Buy ilvl 345+ gear from AH
2. Buy Protector Artifact set (neck, belt and artifact)
3. Buy Drowcraft shirt and pants from AH
4. Complete Spinward Rise campaign for Artifact Weapon
5. Refine Rank 5 to Rank 7+ Enchantments and Runestones if you havent done so already, or buy Rank 7+ from AH
6. Obtain four Artifacts
7. Begin refining Artifact Equipment and Artifacts if you haven’t already
Hope this helps!