I'm with Sparkling. I think you have to have a heart-to-heart with your roommate but I would have a hard time with that. I'd be inclined to clean "half" or a bit more, make my "areas" comfortable for me and ignore hers. I remember in college my roomate and good friend was clean and orderly and I really envied her and loved living with her because she was pleasant that way. I wasn't "dirty" exactly but was a slob but she kept her areas the way she wanted and I let mine "go" (whatever that means :-)

My husband and I are live and let live but I'm still a greater mess maker than he is but could be my perception because I also pretty much run the house and "do"/buy more? We made an agreement long ago that I'd shop/cook and he'd do the dishes. Now though we kind of share all that (he makes breakfast and I sometimes do the dishes if they're in my way or bothering me).

You might try giving her choices when you're doing things/together or ask her to lend a hand ("Would you help me move the couch so I can vacuum behind it?")? Something like "How about if I make dinner and you clean up" (or vice versa) might ease her into thinking of cleaning as a joint activity as well as helping you get to know her? I guess if the person who moved in after me started cleaning right away I'd feel "threatened" a bit?

Talk while you're cleaning or cooking or "borrow" (or pretend to be interested in borrowing) something of hers or comment in an interested way on something you see ("I like the pattern on your dishes, do you remember where you got them?"). Give her the opportunity to feel like you're interested in "her" and not just her mess :-) and to comment on your cleaning "style" perhaps, etc. You could try for "humor" but unless you get to know her a bit first, that might not work/be appropriate or be misunderstood.