You can decide when things get dirty in your house by experience. The houses and the habits of people that live in them change things significantly. Initially I would suggest dedicating a weekend and cleaning everything regardless of how dirty they are (even if they look very clean). Then you can keep an eye on the dirt levels for a while and create the schedule that fits your need. But, here is a checklist of things to clean, which you can print:
http://www.mrscleannw.com/tips/cleaning-checklist.html
And here is a bunch of useful tips:
http://www.mrscleannw.com/house-cleaning-tips.html
I have found this website very helpful. It is created by a professional maid service, but they are not trying to sell you anything.
I hope it helps!