Question about the Ibanez rg350dx guitar!!?

It doesn't matter, string gauge it pure choice, it has nothing to do with the guitar, initially. Most people use 10's or 11's, I use 10's, but don't own that guitar. If you want a thicker gauge for lower tuned playing, or even thinner ones, take it back to guitar center and ask them to 'set it up' for you, they will adjust the action an some other things for you to make it sound right and reduce fret buzz.