The hammer on and offs are one of the most common techniques employed on the guitar. While playing a minor pentatonic riff, instead of playing an E, you could hammer on from the minor seventh (D) to the E. The hammer on and offs are mainly used to embellish riffs, and spice up lines. This technique is also employed during tapping. You hammer on and off with your left hand, while tapping notes out with your right hand (switched for the left handed guitarist).
String bending is also a common technique used on the guitar. Instead of hammering on from D to E, you could bend up the D to an E, adding a bluesy sound. In my opinion, the string bending technique works best for half steps, and whole steps. It is also well served to utilize this technique when bending up from your minor seventh to tonic (D - E) and from G - A (whole steps).
On the electric guitar, the whammy bar is a great tool that can be used. The dive bomb is one of the more famous whammy bar techniques. You play an open string (E, A, or D) and rapidly depress the whammy bar. This action creates a noise that is similar to a dive bomb thus, the technique's name. Also, while letting a long note ring out, you can depress and release the whammy bar to decorate your tone. The whammy bar is also very useful for other-wordly noises that can turn a dull song, into a great one.
The guitar has a huge inventory of noises and sounds that can be achieved by coaxing it the right way. You could spend a lifetime learning these techniques, but just learning a few can add a whole new element to your music.
My name is Luqmann, and I am a Chicago area musician, and producer. I specialize in the electric guitar, acoustic guitar, and my DAWs include Ableton Live, and FL Studio.