One of the more common guitar playing tricks is the "hammer on" that leads directly to a "pull-off" note. The process is very simple, but once you do it you will recognize that sound and think of many places in your favorite songs that you have heard it. To create a simple hammer on, just play the note on the third string in the third fret with your pointer finger. For this discussion let us make the thickest string the first string, and then count up to the thinnest string being string six. Immediately after you strike that note, hammer your ring finger on to the fifth fret of the third string. To create a pull-off note, simply pull your ring finger off of the fifth fret. Try these on different parts of the fretboard to hear the different sounds they make.
If you are a fan of Eddie Van Halen then you are familiar with the guitar trick know as tapping--when you tap on the fret with the pointer finger of your right hand while playing a series of notes with your left hand. If you are left-handed, then the configuration would be the same but with the opposite hands. A simple tapping exercise is to put the pointer finger of your left hand in the seventh fret of the sixth string. Then, instead of plucking that note with the pick, press your left hand pointer finger in the twelfth fret of the six string and then quickly pull off. You have just tapped your first note and are on your way to playing any Eddie Van Halen solo. Try combining hammer ons and pull offs with tapping. Do a hammer on and, instead of using the pick, press down on a higher fret on that same string and pull away quickly. Then do the same thing when you pull off. When you tap you will be tapping the higher fret each time you want to make a note. Practice it on different notes to see how it sounds.
The thing to remember with harmonics is that they do not work on every fret, or on every string. It takes patience and practice to get a harmonic to sound right, so spend some time working on your technique. To practice a harmonic, lightly place your finger over the fret marker in the fifth fret on the first string. Harmonics only work when you are right over the fret marker and not in between frets like you were playing a note. Now strike the string lightly. If you did it right, a harmonic will ring out. If you did not get a harmonic, then keep practicing until you do.