Warrior III (Virabhadrasana III)
1. My hips aren't square to the floor, causing my balance and form to be completely off! The top form mistake I see in warrior iii is that the lifted leg hip is open and not facing down. Both hip points should be pointing towards the floor. I know this may not be as comfortable, but long term this alignment will prevent hip discomfort and lower back pain.
2. My standing leg is bent and my lifted leg is relaxed! This is an easy & important fix. You have to flex through your lifted leg's foot and actively engage it! This is how you will establish balance and core strength. The standing leg needs to be straightened for stability. Energetically lift up through the standing leg all the way to the hip! Think powerful legs for a powerful pose!
3. My neck is straining, my shoulders are cramped and my lower back is arched. Overall: ouch! One easy way to fix this is by taking your gaze down towards the ground about 6 inches in front of you. This will relax everything! Also make sure your core is tight by drawing your navel up and in towards your chest. Imagine your front body is going up towards your back body and vice versa!
PROP MODIFICATION: WALL
Try this pose with your hands on a wall or your hips. Also don't take the lifted leg up as high. Focus more on squaring your hips and keeping your upper body engaged.