Hit up any world bosses, you can do those in premade groups from the LFG window if you need it. Just look for Tarlna, Rukhmar, or Drov. Not everyone loves their loot, but Drov/Tarlna drop stuff that's 650 (belts/chests/gloves/necks), and Rukhmar drops stuff that's 665 (legs/boots/rings).
Check the Auction House as well. You can find some rings, cloaks, amulets, and more on the AH for just a few thousand gold sometimes. I've grabbed a 665 cloak off there once for less than 10k.
LFR goes to BRF this week, and the first three bosses will be available. They're supposed to be dropping 650 loot, so keep that in mind.
If you do Ashran, consider the AshranBuddy add-on for the event timers. You need to wait for the official timer messages to pop before they kick in right, but its pretty helpful for getting through the grind. Before you're done make sure to cash in your artifact fragments. If you have a lot of honor from that, pvp, and events...you can burn it for the Fate Seals so you can reroll on raid drops. The vendor takes honor at 500, then 1000, then 2000.
If you max honor and still have time to kill, consider buying 1-handed weapons to vendor later after the refund timer wears off on it. They sell for around 40g.