Awwww... most of you guys are simply trying too hard, spotlessly clean this, spotlessly clean that and what-not. Just be yourself, don't pretend being someone you're not, and with a bit of luck (always a major factor) you will be just fine. What I'm trying to say here is that you should not present yourself better than you actually are. This may, and most of the time it will, create expectations you will have to live upto in the days/weeks/months to come. If that coffe cup you left on the table in the morning or underwear and some socks in the laundry basket are going to ruin your chances with that girl then you should ask yourself if you ever had any to start with. On the other hand, if completelly redecorating your place would take less effort than to tidy it up your problem is much bigger than just not getting "lucky" with that girl.
If life keeps throwing nothing but lemons at you, make a lemonade!