Here are a few tips to keep in mind.
1. What is the scale of the pattern? The larger the scale, the more you should opt for solid or textured upholstery fabrics. You don't want to compete with the focal point in the room. Try small scale patterns on upholstered pieces as well that read as a "solid" from a distance.
2. What is the style of the pattern? Geometric? Floral? Abstract? This style is already setting the tone for the room so you'll either want to add to that style or contrast from it. It's your choice, but know which direction you're choosing and why. For example, you have a large floral rug in a Family Room, but really you'd like to neutralize the feminine vibe by adding a chunky reclaimed wood coffee table. Voila - the room now feels adult and less girly. This example is a style contrast for sure, but it can work just fine if you know what furniture to add to your rug . Note: you may also choose a design motif in the rug pattern to repeat in other items such as pillows, lamps, end table details, etc.
3. What are the main colors of the rug? So often we view samples from 12" away when we really should be looking at them from 6' away. Lay the rug out and see how the colors read up close and from a distance. Do they bleed together or not? Do they form one solid mixed color from a distance?
What is the vibe of the colors used? Active? Soothing? Earthy? Choose upholstered pieces that will look good on that specific rug color. Note: a color will only appear as a certain color based upon the light illuminating it and the other colors surrounding it! Never rule out a color unless you see it in the room it's intended for OR you just plain hate that color. It best to be open and play with the color combinations a bit. The most sophisticated spaces have unusual color combinations.