Never attempt any freestyle motocross trick until you are jumping confidently and landing the bike in the same position every time. Not most of the time, or some of the time or except for one or two times, do not attemp any freestyle tricks until you and your bike are landing in the same position every time.
To start with try doing a one footer, do them smoothly and try it with each leg one at a time, once you have that down try doing no footers. Make sure you keep your hands on the bars though for now. These basic FMX tricks will help you learn how to control your bike in the air.
The next trick to try is the Fender Kiss, start off by jumping and trying to put your face to the front fender, be aware that the change in body position will alter the flight path of the bike. As you get the hang of doing it start to bring the front fender to you as you put your face to it.
Now your ready for the one hander, stay loose as you hit the ramp, when you are confortable being your hand off the bar a little bit, gradually as you repeat the jump over and over move your hand further away from the bars until you can put your hand on the side of your helmet and hold it briefly.
So now your ready to set some foundations for tricks like the Cliffhanger, Jackhammer, Cordova and Stripper. Remember this is only some prep work, you will not be doing the above tricks for a while yet. As you near the peak of the ramp start to bring your feet up, until you touch the handlebars with your feet, this is called the ankle hook.