I highly recommend Captain Jack Klang's Singlehanded Docking and Sail Trim DVD ...
The key is to use a mid-ship dock line looped around dock cleat and brought back to the helm. Using reverse gear and engine on idle, the boat will be snugged right into the dock.
I am not associated with him or his company ....
he has a web site ... can be found on google
I'd attach a diagram but keep getting error message on upload ???