How I choose a series to collect and read:
1. Jennifer's website has made eBay, ABE, and Amazon a lot of money off of me. That, and a post on her blog influenced a lot of my early purchases. Considering how much harder/more expensive a series can get when she first adds one (see Barbara Ann), I suspect I'm not alone.
2. I'll go down this list, looking for books with copyrights in the 1920s and 30s, particularly those published by Grosset and Dunlap, Cupples and Leon, or A.L. Burt.
3. Once I find an author I love, I'll seek out her other books. See: Adventure Girls, all my Pemberton Ginther titles, Mildred Wirt's many series.
4. I'll sometimes preview a series I'm not sure about on Project Gutenberg or Google Books. See: Polly Brewster.
5. Browse eBay under Books->Antiquarian and Collectible->Children's Books->Series Books. Or if I buy a book from a seller, and they have an unfamiliar title, too, I may add it to my order.
6. Ads for other series in a series that I already have probably won't make me purchase on their own but may make me investigate futher.
The Jane Allen College Series falls under many of these categories. I originally came across it on the Girls Series Books 1840-1991 site but had reservations. While published by Cupples and Leon, I didn't know the author, the timeframe was slightly early (1917-1922), and the theme seemed to be sports. I also incorrectly assumed it was a high school series, which I can take or leave.
Then I randomly purchased a copy of Patsy Carroll under Southern Skies from Jennifer (#5, pt 2). On the back was an ad for what I now learned was the Jane Allen College Series. Automatically, I was more interested--I love college girl books. Googling found Mary Crosson's page on the series, complete with excerpt, and several ebooks. So I spent my day off work reading the entire series. I'll give you my thoughts in a separate post.