As a degree carrying member of the English major club, I think analogies and metaphors are always the way to go when something is complicated to explain. So, lets think of your furnishings and decor (new and junk) as guests at a wedding. Obviously, you don't want your guests sitting just anywhere, or your sweet, conservative grandma might end up next your profane friend with a habit of telling questionable jokes. You love both of these people, but they just aren't right together.
Let's look at some possible seating arrangements:
1. Put everyone with similar personalities together - All your Twilight loving friends and family will enjoy sitting together even if some of them have blue hair while others wear sensible heels. Edward Cullen is a great unifier.
As you can see, the furnishing in this room are not identical or even all that matchy matchy - but they have a vintage vibe in common that lets them get along together. If you follow a few guidelines (pale aqua and red always look great together, an interesting textural piece adds depth to any room, clean lined accessories combat a cluttered look) than you can easily create an inviting room just by combining pieces with a similar feel.
2. Sit all the truly quirky people together - You love your friends, but all of your guests might not appreciate a play-by-play account of Mr. Whisker's last trip to the vet, or having small tufts of fur transferred to their wedding attire, or admiring his picture in Aunt Edna's locket.
If you love something, but it's just a little too odd to work with the rest of your decor, gather a small collection of the items in a pretty container. I've seen this work beautifully with tomato pincushions, matchbooks, vintage hankies, etc. Disclaimer: I really do love cats, but we've all been stuck next to someone who is a little too obsessed with something.
3. Some people are ageless. Your Aunt Jane who loves fashion and tennis and facebook, does not want to be stuck listening to the details of Uncle Kevin's cataract operation. She'd be much happier discussing Banana Republic's fall line with your best friend Kellsie.
Some pieces are so classic that they will work together regardless of whether they are brand new or junk hole finds. The spool leg table and boxy sofa could have been manufactured last week or fifty years ago. It doesn't matter that the styles were originally created in different periods, because both have survived the tests of time and become decor staples.
4. You can mix your conservative and wacky friends, so long as they all know how to be genteel. As long as no one flaunts their summer trip to a commune or lifetime subscription to Rush Limbaugh's newsletter, everything will be fine.
The ultra modern ghost table works with this classic straight backed chair, even though they are incredibly different. This look is possible because both pieces show restraint with clean lines and basic colors. The fact that they are in proportion to one another seals the deal.
5. Keep things in the family. If you seat families together, they're bound to survive because they have to love each other anyway.
You can mix styles, go nuts with colors and textures, but your room will still look pulled together so long as all the wood pieces are from the same tree, or at least stained the same tone. The mirror, lamp, and frame are all the same wood tone, so the graphic rug and lime nightstand are free to be wacky.
6. If you have an odd seat left at a table, fill it with someone known for their tolerance and tact.
This is the white paint, like white lies, can cover a multitude of indiscretions principle. In other words, when in doubt, bring on the white paint. It's a great unifier and can bring elements together that would otherwise clash horribly.
I hope y'all enjoyed my little junk series. I'd love to know all the juicy details of your own junk decor philosophies!