When I look back at fashion styles in the 1980's, I see a moderate progression throughout the decade but most of it was similar. I feel the same way about the current decade that we are in. However, at the end of the millennium there were a lot of changes happening (specifically involving the media) and fashion was not necessarily defined in any way.
1990's women's fashion was what I like to call a transitional stage. Yes, there were many different styles of clothing that emerged during this decade and some of them were fresh and unique. However, it seems almost as though the 80's had laid a foundation for what was to come, and we all know that music had a lot of influence on that. The 1990's gave boost to a media beast known as MTV, which had such a huge influence on the youth during that time. If you wanted to push a specific style of clothing on the young people, you exposed it to them with the help of MTV (and a couple of other television channels).
What am I getting at? If you want to find ideas for 1990's women's fashion, you can get the most help from teenagers and young adults who helped formulate the styles during that time. Archives of music videos and movies are also great sources.