There are a lot of ways to meditate, Eckhart Tolle calls them "portals", but I think it's all the same thing, I'll list my two favorites.
1) Entering the body; you sit and focus on the energy within yourself. Your heart beat, the feeling of aliveness in your hands, your feet, your torso, your head, everywhere. If you focus on it you can go deeper into it as far as you want.
2) Surroundings; Sometimes when I'm on break at work I just sit and focus entirely on the store. There are things that are obvious right away like food timers, peoples voices... But when you start to watch, more subtle things start to appear as well; plumbing pipes, heating radiators, faucet drips. You'll notice irregularities in the floor, in the ceiling, the way the grain of wood goes on a door, the smell in the air... I discovered this when I was forced to do it for a school assignment, what a gift that was!