Do any duty roulettes you have access to and make sure to unlock all the dungeons. More Roulettes unlock as you clear sets of the endgame dungeons that will help you get lots of stones. Crystal tower is awesome for gearing up but you have to deal with potential trolls/idiots however it drops nothing but i80 gear and a lot of mythology stones so if you get lucky you can get a bit better gear fairly quickly.

You can buy i90 gear with the now much more plentiful mythology stones and also buy i100 stuff with the soldiery stones that drop from all endgame stuff. The new dungeons are fairly quick compared to the original dungeons and drop a good amount of stones and they also have i70 gear as potential drops so it's worth taking your time to do em.

Coil 1-5 is easier with the echo buff and can be done through duty finder so once you meet the item level requirements it's another great gear source.

As for leveling up, dungeon XP is crazy good now. If you run the highest level dungeon you have access to you can probably get 1/2-2/3 a level with each run. Don't forget to unlock the challenge log too. It's basically free XP and money for doing stuff you would already be doing.