Here's a beginning meditation exercise that I've found useful. I don't know where I heard it, but I'm pretty sure I didn't make it up. It vaguely resembles Genpo Roshi's Big Mind (vaguely).
I begin sitting and start to think of all the roles I play on a daily basis: father, son, brother, husband, teacher, writer, meditator, etc. Each of these roles has a unique taste and texture to them--who I am as a father isn't the same me as when I'm in the classroom teaching. Often I'll feel a tension associated with a certain role. My chest may tighten, or I'll experience a light burning sensation above my heart. It's important to experience the feeling associated with each role as deeply as possible.
Now I shift directions and go through each one of these roles and say to myself, "I am not a [insert role]." Sit with that until the attendant feeling begins to dissolve; then move on to the next role. On and on until you've exhausted all of the social roles you play. It's a way of stripping the mind bare of all the responsibilities and social functions it habitually grasps onto to create its sense of identity.
This is a good way to begin a long meditation; I find it really calms the body and mind by clearing away the mental debris. Once it's done, you can begin whatever kind of meditation you normally practice--following the breath, koan study, mantra, etc.
Give it a try and tell me what you think.
Image borrowed with permission from flickr user Kat.B. Photography