Personally I find it much easier to back in over the passenger side. I'm able to pivot around in the seat and see that side just fine, rather than trying to squint into a mirror. I have a lot more practice backing to that side as that's the only way I can jack-knife it into my current driveway, and despite how narrow it is, I usually manage it on the first shot these days.
But the key regardless of which way you go, is practice. Again and again and again. Every site will be different, every situation will present its own set of challenges. Every one will teach you something about handling your rig. :)