The in-game tutorial is, in my opinion, somewhat lacking. Here are some tips that I hope help. 1. Note the red zone on the airspeed indicator. Avoid having the arrow in this area. It appears that the likelihood of jammed flaps and/or landing gear increases if you do so for too long. 2. You can restart a flight by pressing P. 3. Except during takeoff, landing, and engine failure, make only fine adjustments to power and angle (tap the arrow key). 4. It is possible to maintain a constant altitude and airspeed without holding any keys. Find a balance between angle and power. Try 92 power and finding the angle. 5. Fly at 2,000 feet to allow recovery time in case of engine failure. 6. Allow for gradual descent. I start landing at 150 miles.
I hope that these help. Post any questions that you may have.