Sabine Ense explains what straightness means and how you can achieve it. Only a horse who is supple can be straight.
Understand what it means to have your horse "in front of the leg."
Imagine pedaling a bike. Step down to the left each time your horse’s left hind leg leaves the ground and step down to the right each time your horse’s right hind leg leaves the ground. Be sure to keep your torso and seat steady and aligned over the horse’s spine.
Explore the definition of "feel" and the prerequisites for it, then try some exercises to develop it yourself.
Learn how to use your "absorbing joints."