One good way to promote your books is to go to book clubs and meet the author events. I attended one recently at a local library , and watched the author try to set up a multimedia presentation. The author used the library provided projector and screen, but a problem arose with the computer. At first, the library people insisted on using their computer. Trouble was, it still used Windows XP as an operating system. While the computer recognized the projector, it was too old to recognize the authors powerpoint file. They sat through downloading an update from Windows. Then they tried to access a Youtube video. The browser on the computer were so old, Youtube would not allow them to log on.
The author finally threw a fit (a good old Southern expression) and the library people let her plug in her up-to-date laptop.
If at all possible., clear these things up with the library (or other public place) before you arrive to speak.