A lot of people throw Dolly Kei in with Lolita, Mori and newly, Otome. While Dolly Kei has some small similarities to these styles, it's not the same, and is extensively different and seperate.
So far as the silhouette of Dolly Kei, you'll notice there's a lot of flexablility with things like shape and hemline.
The hem can range from the very short to floor-length. Medium and floor-length seems to be the most common, but it's definitely "allowed" to go shorter (I myself, prefer knee-length or a little shorter).
The same can be said for "shape". Outfits can range from very bell-like (similar to the shape you'll see in lolita), a-line, to flowy and more streamlined. However, as flexible as all this is, avoid pencil skirts, and tight mini-skirts, really anything that is super "form-fitted", with the exception of your ights of course.
Pants are also an option, but noticably not as popular within the style. When pants are used in Dolly Kei, they tend to be almost knicker or bloomer-like (almost kodona-like), or harem -style.
The colour palette for Dolly kei tends to be dark, jewel tones, earthy, deep colours and subdued/muted colours. The colours can be vivid, but not what you would call "bright". You'll want to avoid florenscents and limit most pastels. THAT SAID: There are exceptions to every rule, and you will see some coords comprised solely of white/lighter colours/incorporation of pastels.
So there are some "basic basics" for you. I hope it proves helpful :) And as always, I'm up for any discussion, question and/or comments :)
(AND, I'm looking for some better pictures of pants in Dolly Kei. I'd appreciate any help in this matter :) )
Next installment: Layering!