Playing with scale
If you're going to wear big or dangly earrings, I suggest not pairing it up with a big necklace or belt because you don't want the jewelry to overpower you. Remember that the focal point should always be yourself and anything that you put on should only accentuate your best features rather than drown you in bling. Sometimes less is more and if you have too many pieces, they will detract attention from one another. Chunky jewelry is definitely fun so don't shy away from big, beautiful cuffs, bold earrings, or wide belts. Remember that the most important aspect of accessorizing is the overall harmony of the pieces and the way they look together and how they accentuate your outfit.
Classical is always in
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Masculine vs. feminine
If you have a man's watch and you think it's too bulky or masculine to wear, think again! Androgynous style is very socially prevalent so you can pair your masculine watch with a couple of feminine bangles and dress it up a little. Also, don't shy away from wearing bow-tie or tie necklaces and oversized scarves, especially if it's in an uber-feminine finish like crystals or silk.
Iconic shapes
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Antique and contemporary
Wearing older jewelry from your grandparents or acquisitions from pawn shops and thrift stores is perfectly great, especially when mixing it with new styles of jewelry. Clashes in culture and time-periods can make for beautiful combinations of accessories. As long as the styles are cohesive and not divisive together, they can be utilized in beautiful ways to amplify your look. Mixing and matching silver with bronze and various colors of gold or pewter also makes for an interesting look, but try not to combine too many kinds of metals together at once. Underneath, you can see various styles of jewelry, some antique, some contemporary, some bronze, pewter, and various shades of silver. There is a cohesiveness between these pieces and they can be mix and matched for numerous looks with teal, brown, or silver scarves/purses and metal-tone belts.
These are merely simple guidelines which aide in the mixing and matching of what we have to create interesting combinations, rather than going out and buying a designated set of accessories for each outfit (which isn't necessarily financially responsible or viable). In the end, it's a matter of personal taste and preference. Some people enjoy matching colors, and others swear against it, as long as you choose colors that are complementary, you will look coordinated, and polished!