I think that when creating a harmonious flow to your house, one should reflect upon their personal style. If you live in a colonial style house, then the exterior should show reflection on what the interior might be like. I like to surprise people, but not create such a stark contrast between the exterior and the interior. This also applies to rooms within your house too. When walking from one room to another, a flow should be maintained.
This will create a great juxtaposition in your house, and also let you easily move pieces around your house to style a new focal point without having to go shopping. This is a tip I learned, early, from my mom. My house has a reflection of a vintage, rustic style. Mixing a large barn house style dining table with vintage kitchenware with splashes of butter cream yellow, vibrant orange and white. That room will lead directly into a rich, saturated red kitchen that houses a collection of vintage items. Any of the things in my house can be moved, seamlessly, into any other room in my house and still fit.
Finding a style for your house, is like finding a style for yourself. Start collecting samples of things that you like. Once you have identified the style of things that you like (you might notice that if follows similar lines in the style of clothing you pick) that is when you can start purging your house of the things that don't fit into your "look". This is also a great way to earn a little extra $$ for updates. If you have a desk that is not in use, or just simply looks out of place, put it on craigslist. Use the money to splurge on a can of new paint, or a new set of kitchen towels. You could use the extra money to fill in the gaps.
Remember, your Simple Sunday Wisdom is to create some harmony in your house. Harmony can make you fall in love with your home all over again.