Start with the Half Kneeling Stretch. Get in a lunge position, and "settle in." Feel the Glute(back) of the down leg working against the hip(front). Get a feel for the muscles around your pelvis. Feel how the muscles on the front and side of your hip(like underneath your pants pocket) work with your glutes to "extend" your hip.
Then do step ups. You can do "regular" with the step in front, or Peterson Step up style, with the step beside you. Start unweighted. Put your "up leg" up, with your toes driven into the step, like the top of a calf raises. Set the step height so your upper leg is parallel to the floor, while you are up on your toes. Then, step up. As you press your heel down, Feel your VMO keeping your knee in line. Then, at the top, feel your hip and Glute working to extend, and finish the move.
Don't alternate. Hit all reps on 1 side, then switch.
"Coach Charles R Polish on the proper way of doing a Peterson Step Up" is a good video.
As you get smooth at the step ups, hold a plate to your chest for resistance. Then, hold a dumbbell one handed, "suitcase style" on the down side, to challenge your hip stability as you step up.
In a few weeks, you'll be ready for the unweighted, lunge in place. Don't alternate. As you get comfortable, hug a plate to your chest. Then load "suitcase style." You can still use the step up as a warm up.
After a few weeks on lunge in place, you can start elevating the back leg. It doesn't take much. Even 4 inches under the back foot will shift a lot of emphasis to your quad.