There are a number of ways to connect two pieces of wood together and each joint has its own name --- butt, half-lap, rabbet, tongue and groove, and mortise and tenon. You can add incredible strength to joints in wood with the right techniques. In fact, when done properly, the wood itself will often fail before the joint does. Strong wood joints are the cornerstone of any successful woodworking project that is meant to last for decades.
Dry fit the joint to make sure the pieces are snug, not loose fitting and not so tight they are tough to put together. This is a good time to make any necessary adjustments or re-cuts that might be needed to ensure a proper fit.
Strengthen butt joints by inserting biscuits. Butt joints (two boards jointed edge to edge) are the weakest type of joint. However, you can add a great deal of strength by including biscuits, which are football shaped pieces of birch, to the joint. Use the biscuit joiner to cut several slots in the corresponding pieces of wood and insert birch biscuits into each slot on one of the pieces of wood. The biscuits will swell when glue is applied so you will need to work quickly.
Using a 1/2-inch wide brush, apply a layer of wood glue to all surfaces that will come into contact with one another. You can apply it liberally, just make sure to apply it evenly.
Refit the joints together.
Using a pipe clamp or bar clamp, pull the wood pieces together with just enough pressure so that the glue just begins to squeeze out of the joint.
Set additional pipe or bar clamps along the joint about every eight inches or so. Make certain to apply even pressure to all the clamps.
Use a damp cloth to thoroughly remove any glue that seeps from the joint onto the wood. Wiping up the spillage now before the glue dries will result in a nicer finish in the end since glue does not take stain well.
Allow the glue to dry completely before removing clamps, at least four hours but preferably overnight.
Remove the clamps and use 150-grit sandpaper by hand or in an orbital sander to clean up the joints. An orbital sander removes a lot of material quickly so be careful not to take off too much. Just enough to leave a smooth joint.