Turn on the forehand and leg yield can be used to teach the horse that the rider's leg can mean something other than, "Go forward." The horse must understand this concept in these very basic movements before you will find much success with any of the more complicated lateral movements.
You should feel like you have to ask your horse to stop, rather than simply "letting" him stop. If he stops when you let him, he is behind your leg.
To successfully maintain the elusive forward feeling hands, imagine that you are pushing a shopping cart as you ride forward into the bit.
Horses speak through their actions. Try to listen to what they are telling you.
Spend time on the basics, such as straightness and suppleness, and the more difficult movements will fall into place naturally.