In order to spice things up, DBV introduces a mechanic called a double jump. If you are familiar with SMASH, or another gamemode that uses a double jump, this is just the same (although, DBV had double jumps first.)
To double jump in DBV, there are 3 ways. The first way is by pressing space (while in the air), or you can either Left-click or Right-click one of the feathers given to you in-game. Each way has it's own advantages.
Your double jump will vary based on where you look. Looking straight ahead will jump you in that direction, and the further up/down you look the less forward velocity you get. Looking straight up or down will result in jumps only going up and not forward.
Your double jump is represented by your experience bar, while it is empty you cannot double jump. Your jump will be recharged simply by touching a solid block on any side. Glass will not recharge a jump, however ice will.
Using the spacebar to double-jump is inefficient and ineffective in every way but one. The only strength of using the spacebar to jump lies in the fact that it takes a while to register, allowing you to travel farther with a single jump. This makes the spacebar jumping a useful final jump in a string of parkour, as it might just give you the extra push you need to reach your goal.
Punching with the feather is another way you can double-jump. You can complete long-jumps, there's barely any time between initiation and actually jumping, but there's one major problem. You won't jump if there's someone in your way. If you hit someone, the jump will not register. This is where right-clicking shines through.
Using the right-click function of your mouse, you can initiate a double-jump. Using the right-click function of the feather is easily the best way to get around. You can complete long-jumps (sometimes even triple-jumps), there's no wait for your jump to happen, and having people in your way will not block your jump. This is the best way to complete every single jump.
By pressing your sneak key (Left-shift by default) you can 'stick' to solid blocks. You can remain in place like this to get the hang of certain pieces, but it shouldn't be used if you are going for a medal.
While not a mechanical change, this is very important for passing almost every level. The best way to perform a long jump is by left or right clicking. By initiating a double jump while your feet are still on a block, your jump will be immediately recharged, letting you jump again in the air. By looking forward and getting a sprinting start, you can get maximum distance.
A long jump is required for the long jump level part, and can potentially even let you skip entire sections of a level if used correctly.
If you get stuck, or frustrated or have a bad time, you can always restart a level by pressing the drop key (Default is Q) Doing so will send you back to the beginning of the level and resets your time. If you ever want to return to the lobby area, you can type /quit and be returned there.