The classic style could be described as the most sober lolita style. It is greatly inspired by the victorian era. The colors are more toned down then sweet and more colorful than gothic lolita. It is a very elegant style that I find easier to wear in public than others. There are a few brands that mostly produce classic lolita clothes, mainly Innocent World, Victorian Maiden, Julliette et Justine, Mary Magdalene, Atelier Pierrot and some more that are not specialized in classic.
The colors you can mostly find in classic are brown, olive green, wine red, black, beige/cream, white, etc. It is rare that you'll find pastel colors in classic lolita.
The patterns that come back often in classic are flowers, lines, old toys/rooms, keys, crowns, vintage items, etc. Often, there won't even be any pattern on the dress.
Accessories are important in every lolita styles. In classic, the headwear is more toned down. The bows are not as big and head eating as in the sweet style. But the bonnets, even if they are quite extravagant, are popular to wear with classic since they were worn in the victorian era. Berets and hats are also a good match with the style.
You don't necessarily need to put lots of jewelry and accessories on your hands or wrists in classic. A gold or silver bracelet/necklace and classic and elegant gloves are often used to make good coordinates. Some also add a brooch or flower accessories to complete the look. Cameos are a part of the classic style too.
As for the purses and bags, they are quite simple in design (with some exceptions). But one in particular consists of a book transformed into a purse, which I find original. The others only have some bows and are often bown, cream or black.
The socks in the classic style often are plain or have some patterns similar to the dresses like flowers, crowns, keys, bows, etc.
Lastly, let,s take a look at the shoes commonly worn in classic. To be honest, some are the same as in sweet. but in sober colors to match the style. Any shoes that looks a bit vintage and/or elegant can do the trick perfectly.
I hope this was good enough to explain the style correctly. I'm not really a classic lolita but I did own some dresses a while ago. I have some dresses again on my wishlist but since I'm a sweet lolita I'd have to buy different accessories to match this style. But one of my goal would be to have a bit of each style in my wardrobe. I don't want to always the same style, it's a good thing to change from time to time.
Next style should be gothic lolita!
I hope you all had a wonderful New Year's Day! I wish the best for all of you in 2012!