I may be stating the obvious, but plant flowers outside that match or coordinate with your interior colors. I have been having a great time with cut flowers this summer, because I have annuals and perennials that look great with the inside of my house (makes me feel less guilty about the weedy mess they are growing in!)
Now, some people take it a little to far and select pets to go with their furniture (we have been accused of that more than once). For the record, our dog was rescued and we chose him because he matched us, not our decor.
My other stating-the-obvious gardening tip is shop now for discount perennials. You have good planting weather through at least October, and you can save more than 50% of the in-season retail price. The way I look at it, the risk is worth the potential gain, especially if your taste exceeds your budget, the way mine always seems to do.