Simple works for me:
1. Lemon oil is for cleaning the fingerboard only, then it needs to be immediately wiped off. I only have to clean mine once a year because my hands don't gunk up. It's a cleaning agent, not an "oiling the fingerboard" agent; fingerboards don't really need oiling, and lemon oil is actually naphtha (dry cleaning and lighter fluid with a scent). Use it too often, and it's really not good for the fingerboard and inlays.
As lemon oil evaporates, it's actually a drying agent, not an "oiling" agent. Use nothing for "oiling" is the best advice.
2. Soft microfiber cloths are actually less abrasive than cotton. A damp one for a wipedown, followed by a dry, clean one. I use these:
http://www.griotsgarage.com/product/micro+fiber+speed+shine+cloths+set+of+3.do?sortby=ourPicks
3. For occasional shining-up duty, I like the PRS cleaner. Waxes simply build up, this stuff works better. I use the above cloths for this duty as well.
4. For polishing out scratches, Meguiar's New Car Glaze is a good polish, but never use it on nitro. I haven't tried the PRS polish, but it's also not for nitro. My nitro Private Stock hasn't needed anything polished out, so I haven't looked into something for nitro yet, and only would do so if it needed it.