How To Jump a BMX bike (Including MTB and DJ BIkes)
We’re going back to basics in this article to cover a topic that many of you requested in our YouTube comments section and that's how to jump a BMX bike properly. While this article is centered around BMX, the skills and techniques discussed here can be used for dirt jumpers, mountain bikes, and nearly anything with two wheels. Jumping is an essential part of BMX that every rider should learn whether you ride street, trails, park or race. Because no matter the discipline, at some point your wheels will leave the ground and you need to make sure you have proper technique.
We'll be breaking down this topic into three major sections: the takeoff, airtime, and the landing. You don't need a box jump to learn on (although it certainly helps) any ramp at your local park, trail spot or even a homemade plywood ramp will do just fine when learning.
Step 1: The Takeoff
Before you ever start jumping the first thing you need to do is read the takeoff. That's because a transition jump with a lot of curvature is going to send you in the air differently than something like a flat bank. On a flat bank you have to rely more on your bunnyhop technique to generate your height whereas a transition jump you rely on pumping that transition to generate your height. Once you've determined how the transition is going to feel you're ready to setup and get speed for your first jump.
Approach the jump at a comfortable speed with your pedals parallel to the ground. This is an important factor than many new riders overlook when first starting out. If your pedals are uneven this can cause your bodyweight to be uneven and you will likely crash as soon as you land. Keep those pedals even and eyes on the lip of your jump. On a transition jump you'll need to generate speed through the takeoff by pumping the transition. This allows you to get maximum height rather than you pushing through the transition just to clear the jump.
As you reach the peak of the lip make sure you are using the entire transition. Many riders will pull off the transition early, even doing a slight bunnyhop off the face of the transition, which can really affect your height. 
Make sure to use the full scope of the transition whereby both wheels are leaving the lip of the ramp and not just the front. Think about it this way; if the ramp is 5ft tall, both wheels need to use all 5ft of the transition. This will lead to smoother and higher airs.
Step 2: The Air
Now that you've got a good feel of the transition and what to expect, from here we move on to the air and proper body position. Instinctively your body wants to get away from danger, hence why a lot of people move towards the back of the bike or freeze up in the air. In doing so they often get kicked sideways or get bucked off the bike. The key to jumping is to stay in an aggressive "attack position" on the bike with your upper body slightly over the bars. You don't need to white knuckle it. Stay loose and as relaxed as possible.
As you're learning to jump higher and further, imagine an arc from takeoff to landing. A lower speed will generate a lower arc. As you learn to add speed and pump off that transition, you will need to adjust the shape of your arc to avoid overshooting the landing. To prevent this, let that speed generate height and not distance.
No matter what kind of takeoff, no matter how steep or mellow the transition is, your upper body needs to be perpendicular to the ground. Keep that in mind as you start jumping steeper transitions because while your bike is going up at a steeper angle, as long as you keep your body in that perpendicular position of not too far forward or too far back, you're going to be alright.
Control the bike, don't let the bike control you.
As simple as that sounds it speaks volumes. As you start jumping higher and higher you may find yourself reacting to the bike in mid air. Instead, stay confident and put the bike exactly where you want it to be.
Step 3: The Landing
Much like the takeoff when it comes to the landing you want to read the transition. Something like a box jump or larger ramp in general will typically have a steeper landing transition. Ideally, you will need to land with both wheels matching the angle of this transition, but if you land back wheel first that's okay. This is especially common when you are first learning and getting used to jumping larger ramps. As long as you are not leaning too far back where the bike loops out, you will still roll away clean. As you get more comfortable push the front wheel down to where both wheels match the angle of your transition to provide as smooth of a landing as possible.
When it comes to landing on mellow transitions or even flat, this technique changes and you will need to land in what we call "airplane mode." In these cases you actually do want to land back wheel first as your legs will act as suspension. Again, don't hang off the back of the bike as this will cause you to loop out, but by pushing your back wheel down first your legs and body will better absorb these harsher landings.
Baby Steps, People
Ultimately this is all going to take some practice, but these tips and techniques should have you jumping consistently within a few hours. Maybe not as high as you want or throwing down any tricks, but keep in mind this is a starting point and all that comes later as you get more comfortable. It's all about taking baby steps, learning the basics of generating height, and working your way from there to jump further and further over time.