Meditation today is a term must abused with many differente significances.
Meditation is a state of conscious. The tecnics of meditation are used for create the condition for the manifestation of this state.
Mediation can't be learned in a book. The best mode is learning it from a master. And one of the best clean way for me is Zen with zazen.
In yoga sutra of Patanjali mediation is considered one of the high level of yoga, level that is reached after a long practice of other yoga levels (asana,pranayama,prathyara and dharana)
I've tried meditation a few times, and finally found something that seems to work with my brain (I can explain but it doesn't answer your question). In the meantime, I tried reading a good deal and learning what I could, so here are the things that stand out for me.
Lots of folks enjoy "Mindfulness in Plain English", and it does a good job of explaining some things, and it got recommended to me over and over again.
For something more in-depth, check out "meditation for dummies". It is a decent introduction to meditation.
For a more realistic viewpoint on meditation, check out Sam Harris. He was pretty skeptical, and seems to not over-inflate the results though he's an obvious believer.
Lastly, I recommend watching Shinzen Young on Youtube. He was really more of a turning point for me, and gives a good deal of flexibility in methods.
The author is both a long term meditator and used to be a neuroscience professor. The book teaches meditation in a stage by stage way which is very easy to follow.
