The real key to mixing high end furnishings with flea market finds successfully is to learn to actually see what you are looking at.
Make choices based on relatedness, proportion and so forth…
Hopefully delight is a primary ingredient too..
One of the most important concepts to master in mixing styles is relatedness: A curve for a curve so to speak. Forget where it came from and how much it cost. Make a game of re-imagining a potential furnishing candidate so that all you see is the color, shape, size, curve, angle, texture and/or design of the item(s) you have chosen for your setting.
Look at the shape of the arms of your big upholstered pieces. They should relate to each other by similar curves or by similar square-ish-ness. The same is true about furniture shapes. Clean-lined furniture styles with similar legs play well together as do furniture styles with curved edges and legs.
Look for repetition or similarity. How did the pieces reference each other? For example, you might have two lamps that are different but the same height and/or material. They could work flanking a sofa on either side if they both have the same type of lampshade.
How about patterns that echo some component of each other? This visual process is how great designers manage to mix the best with the common to get a stunning result.
When you work this way, the provenance of each item becomes coincidental. An unexpected combination of elements and/or a mix of style “opposites” can elevate the aesthetic level from the “nicely decorated but ordinary” to “A Really Great Looking Room”.
Once you have ordered your major pieces into shape agreement, you can throw in a few opposites to create interest. In a “curve dominated” room, a clean and straight lined piece will stand out like jewelry. In “a room for squares”, use curved vases, and other rounded accessories. Extravagant bouquets of lush petaled peonies will lend harmony to the straight edges as well.
You can have a piece that seems like a random selection if you create an overall sense of balance and order within the structure of the room design. Symmetry is good. A few items with deliberately straight lines adds balance and interest if there are a lot of curves in your composition, or vice versa.
Going the extra mile: with all of the pieces in place as described, you can move toward a concept of contrast and juxtaposition. This concept works best if you use pieces from different time periods. For example, what if you placed a very modern steel and leather chair from the 50’s next to an antique Japanese Tansu? The design quality of both stands out in high relief.
Pulling the above approach off so it looks like you know what you’re doing is tricky. It can backfire to the point of complete discord. As an anchor to refer back to, always remember that you are creating a composition in three-dimensional space. Put everything in place and ask yourself if your vignette looks balanced. Does the scale work? A small delicate item sitting next to a massive heavy object just looks wrong. Do all the assigned furniture and accessories work in relationship to each other or is any one piece placed too far out of the picture? Do you have a range of light, medium and dark tones? Is there a color punch somewhere?
Don’t binge on too much assorted “awesome”. Keep it simple. When styling a room, remember that between your walls, floors, ceiling and furniture, only one element can be the star performer in any given room, with all other details playing a supporting role.
Starring roles are like alpha dogs. There can only be one at any given time and place without a fight for attention.
All great designers, know that Magical Thinking has its place. Any sentence that has “should always”, “should only”, or “should never” in it, is a decorating mental block. The only “should always” that will net great results for you and your home is “have an open mind to new ideas”.
There will always be mistakes…and sometimes they become your favorite things.