Lolita is a fashion subculture from Japan based on Victorian clothing. It has many subtypes, and my favorite is sweet lolita. More Rococo-influenced, this style features pale colors, pastels, bows, candy and fruit imagery, and anything falling under the "sweet" label.
Skirts with border-prints are incredibly popular. Typically outfits match head-to-toe (Source)
Makeup is kept natural. The idea is to look childlike - neutral eyes, pink cheeks, powdery skin. Nails are usually a very pale pink, lavender, or mint.
Yes, an American girl on the left. Two-tone hairstyles are also popular, where 1/4 of the hair is a different shade. Pastel hair is also very common.
It seems a little over-the-top, so how can we use this as inspiration? Here are how some real girls are doing it:
Mixing textures like rosettes and lace give a nod to femininity. Pale florals are sweet and subtle.
Very understated - it's all in the pink socks and shoe - whereas on the right, it's all about ruffles and flowers.
Images from Chictopia.com; all other unsourced images from Tumblr. If you know the source, posting would be much appreciated!