The single leg deadlift can be difficult to perform because it requires a great deal of balance and stability. Here are a few tips to improve its effectiveness:
Pick a spot on the floor (about 10 feet in front of you) and lock your eyes on it -avoid glancing down at your feet. Looking in front of you will keep your head and neck in a better position which may improve stability.
Take your shoes off. Many athletic shoes have a big, squishy heel that will only add to your frustration. With out shoes you will be better connected to the ground and create a more stable foot.
Create tension. Screw your foot into the ground. Brace your core to maintain a neutral spine as you hinge over. Keep your back leg straight and in line with your upper body. If you are holding a weight, squeeze the handle and engage your back muscles. Finally, keep your hips square to the ground; dont let them twist open as you hinge over.
Slow down. Lock everything in and slowly lower yourself in a controlled manor. Whipping yourself down will create more instability.
The Sldl requires practice and patience. First, try performing it with support (a wall, pvc pipe, etc.). Once you feel comfortable with the technique, go ahead and practice on your own. The benefits you experience from an sldl are worth the time and effort.