The purpose of Hockey tape is to keep moisture off the stick and to keep the hockey puck from sliding off of your blade.
Get a Better Grip on Your Stick
You also need to create a knob on the handle of your stick with tape to keep it from sliding out of your hand. If you are a defenseman, or even a defensive forward, you may prefer a larger knob so your stick won't slip out of your hand while pokechecking.
Here's a tip that will not only save you some hockey tape, but will give you a better knob: Unravel about 12 inches of tape from the roll and then twirl the roll.
This causes the tape to tighten into a serpent like shape with the adhesive part on both sides. Starting at the top of your stick, roll the hockey tape around the shaft, as far down as you'd like it to go. You can even roll this tape halfway down the shaft of your stick so your lower hand can get a stronger grip while stickhandling and shooting (like a lot of European players do for instance Sergei Zubov, Marian Hossa and Jaromir Jagr).
This layer of hockey tape will now serve as the foundation for your knob. Now roll the tape the same way when taping a blade over this foundation to give you the thickness you would like. You should have a knob thick enough so you can pick up your stick if you drop it, but not too thick so that it interferes with stickhandling.
Tapinng The Blade
When taping their hockey blade most players start at the heel and tape towards the toe in one continuous strand. Make sure the hockey tape is flat against the blade so it doesn't bubble or create folds while taping. If using a wooden stick it is also a good idea to tape the stick just above the point where the shaft meets the blade, for added reinforcement as this is a common area where the stick cracks or breaks.
Add Some Wax
After taping your stick, you may want to use hockey stick wax . A lot of players use wax to ward off moisture from the ice from their blade. The wax serves many purposes: by warding the moisture off it allows for better grip on the puck, and also protects the tape job from getting too wet.
You may also want to consider using some grip tape to put over the knob that you created. This kind of tape, although a little bit more expensive than regular stick tape, is gentler on the palm of your gloves. Might be worth it in the long run since new gloves or re-palming the existing ones cost a heck of a lot more.
Best Tape Job
It really depends on what you are comfortable with. Bobby Orr used to tape only two inches of his blade, while Wayne Gretzky taped his from heal to toe.