Dirty dishes really don't bother me. I know it bothers one of my flatmates, but I don't believe in wasting water washing up a plate, bowl and a fork when it can wait an extra day and have a couple more items in it to justify a wash. I come from an area where our water supply used to come from the river and was filtered through our own system, so I'm used to preserving water and making the most of it. I've explained this to them, but they still get irked about it. Its not a total mess, its a few plates and forks waiting an extra day if that. I don't give a **** if I don't pay for my mains water bill, when I get a house and have to pay for the amount of water we use I sure as hell don't want that bill to be through the roof.
I think my do is definitely approach problems in a cam manner, because my flatmates were not calm about said thing above at all and I'm not being funny, but if someone is being a complete dick to you, you don't want to solve the problem. Whereas if they're being calm and reasonable about it, you're more likely to want to get things done.
I think mutual respect is a big thing, you've got to respect everyone has different ways of doing things and everyone is from different backgrounds and you have to be lenient. No housemate is going to be perfect. You think you're doing everyone a favour by cleaning up for example, no. You may very well be annoying someone by being a "neat freak". You've just got to filter out problems I think. If someone is doing little things that irk you, ignore it. Unless it becomes a big issue. Don't make a mountain out of a mole hill. You gotta deal with other humans and their ways.