Clutter is going to complicate things. When I moved from a two bed flat to a studio just before I married Mr A, I tried to keep everything, but cleaning got to be too much. Over the next few years, I got rid of probably 75% of what I owned. Hands down, getting rid of the clutter is the biggest step towards keeping a house clean.
You can clean around clutter, but your house won't be clean or neat. [Edit: Plus, it will take forever for you to clean something that would be relatively quick to clean if you're shifting stuff around]
It might sound like I am a bit hardline about it, but I had to go around asking myself if I really needed this thing or another, if I really loved it, or if I could use it to make money in some way (value, utility). On the last one, I had to really look at it objectively and not keep something that might be useful someday or have a great value at some point. [Edit: Everything you do keep should have a home, but you shouldn't figure out the system for organising it until you've decluttered]
When I moved here, I got rid of almost everything else. I kept at least one thing from each of the people I loved to "remember" them by, but if I was keeping something just to remember them and I had other things, I got rid of it.
Decluttering has done so much to help me centre my life. My house is my home and not a warehouse for stuff. I think the reason I was so unhappy with my inlaws is they were incredibly cluttered people, and nothing I could say would convince my mother-in-law to throw things out. For instance, she kept the little plastic bit from the microwave they threw out. You know, that ring the tray sits and rotates on? I told her that keeping the glass tray was (somewhat) understandable because she could use it as a tray, but she should throw out the plastic bit. She said she was keeping it because they might get a microwave it would fit (it didn't fit the new one) and that the part might break on it, so she had a spare. I asked her what the chances were that that would happen, and she couldn't answer. I asked her what the chances were she'd be able to find it if it did happen, and she couldn't answer. It's a small little piece of plastic, but multiply that times how many things (like she collected empty Nescafe jars), and you don't have room for things that matter. It also meant that Mr A and I had no room outside our room for anything.
Now, I am not saying you're like my mother-in-law, but I have a feeling you are more like I was. I can't tell you how liberating it is to get rid of even a small or moderate amount of clutter.
I have problems with Mr A sometimes. He hoards paperwork, old books [edit: not talking about first editions or books he cherishes, but stuff like "Startsky and Huch" or whatever they're called. That series has been the friggen bane of my existence, but he claims he plans on reading them again before he gets rid of them], and so on. But he agrees in principal and is working on it. He is so much better than he used to be, and I think that has made a huge difference.
Good luck. If you want, PM me and I can point you to more online help.