I've read maybe a dozen books on vipassana meditation (the type usually posted to HN), zen, and mindfulness. The two best practical books on meditation I've read are:

1. The Miracle of Mindfulness, Thich Nhat Hanh

2. Mindfulness in Plain English, Bhante Gunaratana. This one is free online, though the paid copy is a bit more edited for clarity.

My primary guide is 1. It's concise and provides just the right amount of breathing exercises to help me focus while I "sit." 2 is more comprehensive but I've found it a bit too scattered, with too many tools to help with breathing that I go in circles attempting different ones. Most people I think employ a couple and ignore the rest. 1 is much better written and just a more cohesive book than 2 IMO, but they're both great books and either one alone works well as a guide to meditating.