There are many systems, however I would suggesst the following:
Shimano SPDs - basic system available for most types of riding, big benefit is that SPD shoes can generally be walked-in as the cleat is recessed into the sole of the shoe. Good for comuting and touring in particular. Downside is that the contact area with the pedal is fairly small. Good lateral float on the pedal, good for starters.
Shimano SPD SLs are road specific, much larger contact area, have to walk like a duck, slightly less float better contact though for road bikes.
Look Keos, similar to SPD SL, good contact area, float dependant on cleats attached, walk like a duck, good contact area for road bikes.
I'd go Keos myself on a true road bike..