Since you're Lv70 be sure to do your daily roulettes as your lv70 for mendacity tomes. You sacrifice the chunk of exp you can get on a leveling class but in exchange you get the tomes you need to improve your 70 class(es)

Use those tomes to buy the i360 gear (or i390 if you build up enough genesis)
Start by replacing the lowest ilvl gear you have just to get your avg ilvl over the i300 hump.

After that run the 70 dungeons for i300-345 gear (depending on your ilvl) to slowly build up your ilvl along with getting more mendacity and genesis tomes.
You can also hop into deltascape and the 24m to break up the dungeon runs. There is also eureka if you dont mind the grind to up your job gear a little bit.