Two principles that will help you work toward your safest greatest range of motion in all of your joints are Reciprocal Inhibition and Proprioceptive Neuromuscular Facilitation, or simply PNF.
More of a phenomenon than an actual technique, reciprocal inhibition is something the body does naturally to protect itself from injury, but it can nevertheless be accessed consciously. As previously mentioned, many of the muscles in our bodies work in pairs. Every agonist has an antagonist, and vice versa. Reciprocal inhibition means that when the agonist contracts, the antagonist relaxes.