Neat people often feel a desire to keep things clean and organized. It becomes second nature to them to clean up after themselves and to keep things in a relative state of tidy. So when a neat person lives with someone who is more inclined to be messy, it can cause quite a few problems. Use these tips to negotiate a cease-fire in the clean wars in your home.
Ignoring the problem won't work. You'll need to face it honestly, but respectfully. The truth is that clutter and mess can cause people who are naturally neat quite a bit of anxiety and stress. On the other hand having someone nag constantly can do the same thing to someone who is more casual with their messes. Schedule a time and a neutral location to talk about the goals you both/all have for your home. Recognize that each person's opinion is valid and that compromise will be necessary.
Dirty and messy really aren't the same thing. Dirty implies that there is actual dirt, grime, leftover food, or mold present in your home. Dirty is gross and can potentially make people sick. Dirt invites damage, stains, and insects. Messy is more like clutter or items in places where they don't belong. People who are neat sometimes combine these two terms, but they really are different. It's totally fine to have rules about getting rid of dirt. Messiness is where you'll need to compromise.
Start by describing your ideal home. You might be surprised to find that you and your messy roommate agree on many items. At this point you'll likely have to start compromising. What happens when someone is in the middle of a project? What should the living areas of your house look like at all times? Who has duties in which rooms? What are some daily, weekly, and monthly chores? You don't need to compromise on health and safety issues, but you may need to on more subjective items like how a room looks.
One thing that really helped me was to take pictures of what each tidy room looked like for my family after we'd compromised on a basic level of clean. My kids referred to the pictures to make sure they had put each room back to the way it needed to be. Cleaning checklists can also be a useful tool once a routine has been agreed upon. It helps others to know/remember what is expected of them. Don't be tempted to add items that weren't agreed upon to the lists without group consent. That's an easy way to cause a revolt. We don't want to give our families any extra excuses for not cleaning. Recognize that children may have their own cleaning excuses and need separate solutions.
In my family we've agreed that common areas are to be picked up regularly and frequently. Our own personal spaces are a little different. They aren't allowed to be dirty, but the level of messy is a little more lax there. Does it still drive me crazy when I walk by my daughter's room? Sometimes it does. And when her room reaches a state that violates safety and health, she is required to do something about it. Until then, I try to be tolerant of the mess.