Your comment is a breath of fresh air. Meditation really is very very complex. Primarily because there is the visible side and then there is an invisible side, and the invisible side is not only different in different traditions, but also it is supposed to be different for each practitioner.

Even if you focus on Muslim meditation traditions, there's a huge variety. The Chishti tradition considers a state of dance to be meditation (eg the twirling dervishes) where as the Naqshbandi tradition is more inline with the Buddhist side that involves sitting still and focusing.

> Sure, there are some key concepts common to all like "awareness" and "mindfulness" - but awareness and mindfulness of what?

This is perhaps the most fundamental difference and its astonishing how most "meditation guides" completely ignore this part. See, while a lot of people sell meditation as a relaxation technique, almost all of the original traditions have much deeper goals than this.