Find a good set of audio tracks (I like bodhipaksa, but there are many) and set aside some time.

Even if it doesn't seem to have much effect on the first try, keep going, it takes time to learn.

The key is that you're learning a new skill, like running, catching a ball, or riding a bike. When you learn those sorts of things you create a mostly sub-conscious mental association between certain triggers and the response to them. When you learn to meditate you create an association between some sort of trigger and a state of relaxation. The trigger can be anything, often people use a combination of posture and some sort of chant to help. For myself it tends to be some combo of breathing out and relaxing my shoulders.

You can use the same technique to tap into other mental states but it may be more difficult.

Just don't mix it up with any fad diets. I have a friend who swears he received incredible visions while meditating and following the Beyonce diet (this consists of living on maple syrup + cayenne pepper for a month). Uhh no dude, those were hallucinations caused by your brain slowly dying...

For actual meditation, I'd recommend apnea AKA freediving.

I highly recommend doing a 10-day silent vipassana course. You can find centers world wide at http://dhamma.org They are free and are non-religious, and tremendously helpful.