By definition, a private library begins with...books!
If you don't have any, you need to get some.
Even more preferably...free!
There are a number of ways to arrange this:
Get books as presents (from friends, relatives, etc.)
Get books as hand-me-downs (from same friends, relatives, etc.)
Get cast-offs from libraries. (Not all libraries that "weed" their collections sell the stuff they don't want. Sometimes they give the books away! Look for a "Free Books" table next time you're in your favorite library.)
Trade away books you don't want for books you do want. Great sources for trades are the above mentioned friends & relatives, local book groups (if you're the "joining" type), as well as ventures like BookCrossing
And don't forget to check out LibraryThing
Of course, sometimes you just can't get what you want for free, so in our next post we'll look at some low-cost (but not free) ways to find those first few books you'll need to build your private library....