Opinions differ on what constitutes meditation -- for some, simply taking five minutes of their day for solitude is enough -- but if you're having difficult getting started, there are a few tips you can try.
It goes without saying, but you should avoid caffeine, cigarettes and other stimulants (even some teas) beforehand, so resist the urge to fire up the kettle, at least until you're done.
Tom Casano over at the Huffington Post also recommends not "trying to hard", or even doing a short yoga session to prepare:
Meditation at its best is soothing, relaxing, and effortless. It's merely observation; observing your breathing with your conscious awareness. So there is no real effort involved, just being consciously aware. So don't work too hard at it. ... By stretching or doing yoga before you start meditating, you'll prepare your body to sit in one position for a long time. Yoga and meditation go hand in hand. Even just rolling your neck and stretching your back beforehand can help you stay comfortable for longer.
The last thing you want is a cramp just as you're getting settled, so at the very least stretching is a good idea. If you still need more ideas, Casano has a solid list of things you can try to get into the mood (or spirit) of the endeavour.
20 Meditation Tips for Beginners [Huffington Post]