Here's a very simple router jig you can make with plywood scraps which offers perfect accuracy for dadoes (grooves) and allows you to see exactly where the dado will go. It's dedicated to work with your specific router and one bit, so label the jig and make a few of them! You can make continuous or stopped dados with this jig and you'll see before you cut exactly where the groove and the stop will be. I find it is faster than trying to set up a table saw or radial arm saw with a dado blade.
This router jig is similar in concept to the circular saw jig I showed in an earlier video here:
https://www.youtube.com/watch?v=oiSz7kPwFY0&index=15&list=PLD4oAOZqK9mB7tUGxFEvk6q-sXui96kA6
