Before you go to a paint store, or a furniture store, or any type of place in search for something for your next project know what your going for first. For instance, if you're going for paint, then buy a sample of the color you "think" you like in the store. Bring it home and test it out on the wall your going to use it in. I suggest buying a paint deck in your favorite paint brand. That way you don't have to run back and forth to the paint store.
Next, you should have a plan. NEVER EVER JUST WING IT!!! What I mean by that is don't just go for it. Plan your project out first. Think of everything you want in the space (fabric, colors, accessories, etc..) and take sample pieces with you everywhere you go when your searching.
Know your space. How many times have you purchased big pieces and realized that they don't work well in the space? Get to know my friends Tape Measure and painters tape! Measure your space. And if you still have problems seeing the pieces in the space then that's when painters tape come in. Tape off the floor in the space where you think the piece would work in the measurements of the piece.
Please, please, please let your space flow from one to the other. When you are considering a color scheme in different rooms like kitchens, dining, living rooms, then try to do the same color family or colors that are close on the color card. Don't do red walls in the kitchen and a "toasty" brown in the living room that is somewhat open to the kitchen (hmmm I think I've seen that somewhere!).
Last, be fierce with design, but know what your doing. Don't do black kitchen cabinets if you're planning on moving in a year or two. The next person may not see your vision. So if you have cabinets that need to be painted, try a nice creamy white and accent with black accessories. Don't do chocolate brown walls and your furniture is black!