Whenever I assess or try to predict trends, I think opposite of whatever the trend was during the prior season. So if neon brights are in during the spring of one year, then look for an introduction of pastels the following spring. There will always be a stable transition group of colours and those are known as basics - black, white, light and dark caramels and taupes, and dark blues.
As far as jewellery goes, just think back to feathers which were all the rage in the early spring of 2011 but by the spring of 2012 they were being phased out, although you did occasionally see some feathery accessory but certainly you knew they were on their way out. Chandelier earrings have been around for several seasons now with only slight changes in the colour of the gems or glass. So when buying chandelier earrings, the longest lasting ones will be clear glass, opaque whites, black semi-precious gems, metallics - those tones will take you through the cycle of chandelier earrings which just may be a 3 to 5 year period from beginning to end. Feathered jewelry recently has only managed a year long stay, even though one online source is predicting more elaborate feather creations for the fall of 2012.
Spring and fall are the best time to incorporate faddish colour elements like fuschia, turquoise or orange. These will stay around for a short time and then the basics will kick in and be your reliable base choices. That is why it is a good idea to copy men's fashion by buying several tops, shirts and blouses and scarves (equivalent to the shirt and tie) in the faddish colours and keep the major clothing item purchases in the basic colours.
If we analyze what has been, we can predict what will be. And so from what is, here's a closet analysis and five trendy consequences for the winter of 2012:
1 Orange was hot for Spring 2012, so I think we can safely predict that we will see orange for the fall with infiltration to winter and then a phasing out. It is often a fall colour anyway because of changing leaf colour, pumpkins and Hallowe'en, which predominate October and November, at least in North America.
2 Studded shoes, purses belts, jewellery, especially bangles and cuffs, gloves, and the occasional jacket will also continue for the fall of 2012 (as illustrated in the French Marie Claire, September, 2012 issue) and the heaviness of the metal studding is conducive to winter.
3 Colour blocking will evolve into tonal blocking of a colour. Evidence for this comes from the blocking of blues by Lacoste.
4 Animal motifs will continue their popularity in both fabric and jewellery design. Just remember not to wear too much of the print or mix them up too much. It seems you can only get away with that if you are a celebrity.
5 After over twenty years of de-emphasizing the shoulders, shoulders will be larger again but softer and rounder, not in the angular way of the 1980s. This will be particularly easy to accommodate in winter outerwear.