Asking ARKS veterans: please help me know the best way to raise RNG.

Hello arks, Im new to pso2, and im sorry if this info is easily accessible, i just havnt found it.

I would like to equip a new rare i acquired but am short on RNG. I tried making a ring to boost my RNG by 20 so i made a +20. Ring. Yet that didnt do the trick. Sorry for being a nub. Lol. What can i do to up my RNG to equip this weapon. Thank you so much!

What is your main class, subclass, their levels, the type and level of your Mag, and character gender/race?