The biggest mistake I see riders make when trying to jump is the lack of compression and explosion just prior to the jump. If you don’t compress and explode, your bike will behave very similarly to a rock. Gravity will get the best of you (and your bike) and will promptly get pulled down to earth — not typically the desired result.
1. Prior to attempting the jump, get off your bike and inspect the lip of the jump and the landing. Figure out what the best angle for approach is and exactly where you’d like to land your bike. Once you’ve determined the best line, stick to it — it’s very difficult (and potentially dangerous) to change your line while flying through the air.
2. As soon as your front wheel gets to the face of the jump, compress your bike into the ground. Your elbows should be out, knees bent — full Ninja (ready) position. Note: You don’t need suspension on your bike to compress it — compressing is merely the action of throwing your weight downward.
3. Just prior to reaching the lip of the jump, explode! This explosion is a quick pull up with your arms and legs. If your timing is correct, you will sail right over it. If you are riding uphill, throw your weight forward as you go over an obstacle. If you are riding downhill, you will need to shift your weight backward as you go over it.
4. Once you’re flying, relax and resume your Ninja (ready) position and keep looking forward to your intended landing spot.
5. Push your bike down onto your desired landing spot to increase your traction. Your arms and legs are your primary suspension when landing — your body need to soak up the impact. Relaying on your suspension solely tends to cause a hard landing and a potential for loose of traction.
That should be enough to get you started — I recommend starting with a small obstacle at first. As you progress, experiment with controlling your landing, both wheels, rear wheel first, distance, height, etc. Note: Avoid landing on your front wheel, that usually doesn’t end well.
As your confidence (and skill) increases, pick bigger obstacles, going up and down hill while jumping, experiment with your air-time and HAVE FUN!