Sit on a flat surface, lowest to the ground is best.
Rest your hands, palms down... or up..., on your knees and close your eyes as if going to sleep.
Now, imagine a white void, nothing at all, now "create" a black hole of darkness. Jump into it.
That's what I do when I meditate, it works every time.
These thoughts are geared more towards learning to meditate. I'm sure there are quite a few more advanced guides out there but this might help someone get started.
I was taught that meditation was NOT the process of completely emptying your mind but more like learning to 'ignore' the buzing for a time. Contrary to popular belief the mind's natural state is to continue processing throughts and images while awake, or to dwell on problems until they are solved. Meditation is a tool to help us learn to let go of these troublesome thoughts long enough so it is not intrusive to whatever you are trying to do at the moment. It is also very good for intense focus on whever problem you are having... not stressing mind you, just sitting to explore possible solutions and outcomes. This last one I do before bed from time to time if I have something I want to try to dream an answer for.
Most forms of meditation I have seen start with a systematic relaxation of your body by starting at one end, usually the feet and continuing up the body. There is nothing wrong with starting at the head though if that makes more sense to you. First do a little light stretching. Then tighten each muscle group for a moment, and release/ relax it. I personally talk or think myself down into a meditative level as part of this relaxation process.
Next create a mental image to keep your mind busy. I tend to lean towards fire, a candle flicker does the trick. I know some people use a stone or flower or any simple item.
(*Little side note - If this part seems hard you can try practicing outside of meditation time by holding the item in your hand to study carefully with your eyes and fingers, then closing your eyes to try to recreate the image of the item in your mind's eye. So that you don't wear yourself out on this. Try it several times a day in very short sessions.)
I wouldn't worry too much about the time spent here since it can interupt the session to keep checking how long you have been at it. If it is too much of a worry for you then you can set a timer for yourself and tell yourself when that timer goes off then its time to work your way back to full consciousness. If you do set the timer then typically 10 to 15 minutes is good for starters.