Book fairs and conferences are excellent places to meet other authors and potential readers. The energy in such venues is magical, but learning how to use it to your advantage takes practice. Many authors, myself included, are introverts, so your first experience in such an environment can be intimidating. There are also numerous conventions and protocols for how your table or booth should be set up. Thus, before you take the plunge, visit a few to scope them out so you know what to expect.
Your best bet is to concentrate on those close to home. Not only can your local fan base find and support you more easily, but others in the area will discover you as well, perhaps bringing opportunities for other appearances.
However, even in your own territory, selling enough books to cover expenses is unlikely until you’ve developed a strong fan base. This definitely applies to venues that require hotel stays or, heaven forbid, airfare, though if combined with a vacation, such bills offer a nice business-related tax deduction.
The main thing is not to be discouraged by expecting too much. Just include the cost in your marketing budget and count any book sales as a bonus.