There are countless approaches to joining two boards together, and our job as woodworkers is to choose an appropriate joint for each application. A good joinery option to have in our arsenal is called a lock joint, which is commonly used on projects that include drawers. This joint essentially combines a table saw dado on one piece with a rabbet on the other, and the result is a joint that is simple to create and assemble, providing sufficient strength to withstand significant abuse over the life of the piece. The only prerequisite is knowing how to use a table saw, and to have access to a table saw dado blade. The steps necessary to form this joint are straightforward, and in this video George provides detailed instruction on the setup, cutting, and perfection of this joint.
Set it up once and run them all through
The key to setting up an effective table saw dado is to carefully set the fence and blade height, then patiently modify and test the setup until the perfect configuration has been achieved. After these variables have been taken care of, it is a good idea to run all the pieces through that will use the same setup, which provides both efficiency as well as consistency. After all similar pieces are milled, you can modify the setup for the mating piece.
Sneak up on the fit
In your initial setup, it will be important to position the fence and dado blade height so that you err on the side of leaving a bit too much wood. That way you can carefully make adjustments toward the perfect fit without sacrificing the work piece. That is good practice for the creation of many woodworking joints, as it is easy to remove more wood that to put some back on.