The most important thing to remember in decorating your home is editing. (The same is true of organizing schedules and handbags). Decorating is not about acquisitions but rather about fine-tuning what we have, ruthlessly. Clutter is just that, and a nuisance to tidy and dust. Needless to say, the one design category where accumulating may be acceptable is when you live in an old farmhouse in Wales and you are unaffectedly doing "Sweet Disorder."
All you really need for great home design are a few great pieces. The selection of these pieces may vary. Look for a great painting or photographs, an amazing old piano, a serious piece of furniture or chandelier. You still must take care to mix these with some other pieces, but the overall viewpoint will be distinguished by the more designed items.
The best color that I have found for walls is named "Linen" on many paint lines. Use an off-white color to contrast slightly on the trim work and doors. If you want to go bolder, consider doing one wall in Rothko Orange or Georgian Rust and the other walls in a warm but neutral coffee shade. This way, the overall look is not overwhelming. Several paint lines are now offering small, reasonably priced "tester pots" that allow you to try the paint on the wall for color and quality.
When you are purchasing a few great pieces, do not forget to buy several area carpets in wool or silk. Traditional patterns with dark ground colors are the best, as they wear well, do not look dated and do not need a lot of cleaning. Wood floors are then the main flooring. Sisal or coir matting is also good as area carpets, and it can be replaced when needed.
It is best to not cultivate nor indulge in any specific style. Waking up in a lime green bungalow or the mall's version of French Country is just not okay. Well-designed pieces that you appreciate will naturally sit well together.
Do not forget the shmatte! When you go to a fabric shop or showroom, take swatches of the fabrics that you like. Then, ask good questions about the pieces that you have chosen, to be sure that the fabrics will be suitable for specific rooms. For example: Is the fabric durable enough to upholster a sofa that is used by children and dogs when lounging? Will the fabric fade in a sunny window if I purchase it for drapery? What is inter-lining? I am looking for fabric to recover my dining room chairs. Do you have a fabric that is Shabbat-friendly; i.e. crowd and stain resistant? More to the point, fabric that is Uncle Manny-proof?
Just a quick note about children's rooms: avoid an abundance of novelty and storybook prints that have a theme in mind. Avoid themes altogether.
Being a designer, I naturally want to style everything, and I confess to being overly concerned about my domain. Perhaps my daughter, like all children, will rebel against her mother's sense of aesthetic control. I tease myself with the thought of her someday living in one room with naugahide seat cushions and plastic mini-blinds. She will be under-styled, unfussed, and, no doubt, altogether happy. And that's the point: the real secret to designing is to help yourself feel at home.