Consider the shape of the furniture when choosing fabrics. If you're decorating a curvaceous piece, it's advisable to stick to solid-colored fabrics, patterns, or textures with a unique orientation that may not work well. A pattern that looks great on a piece of fabric may not look great once it's chopped up and put back on the sofa, especially if it's a tricky ornate shape.
Also, consider the size of the furniture. We love larger pieces, like sofas, in rich solid colors or classic neutrals so you don't get bored over time. Liven things up with smaller pieces, like a great chair with a bolder color or pattern. Think about other furniture in the room, especially other upholstered. You need to make sure the colors, textures, and patterns work well together.
The easiest way to make sure you like the trim material on a certain frame, and the feel of sitting on it, is to choose what you see in the store. If you're in love with a fabric that isn't shown on the floor, ask for a sample that can be draped over furniture to get a better idea of how it will look. If you choose the custom option, make sure you see a large sample of any patterned fabric so you'll see the full theme and full-color palette. Once the piece arrives, a little due diligence will help you avoid a big surprise.