Run your bosses every day.
Here's a list of bosses you can do based on the last time we saw your damage range:
Zakum normal and chaos: 100
Horntail normal: 50
Gollux (easy): 50
All four RA bosses (You need two people so bring someone to carry you): 200
Hilla: 50
Hard Hilla (Need two people, if you have a 1m range friend to solo for you): 50
VL: 50
Normal Ranmaru: 50
That's 600 RP every day.