I can't really give you an answer/tip in animation but I can give you some tips on the logic.

When you first press the jump key, Run the "Jump" Animation.

The "Jump" animation can be done in few ways. One way is just to give the illusion that the character pushes them self upwards by extending their legs out. Another way is that if you have a delay between the jump key and the actual jump is that you add in a "1/2 crouch" motion to them.

In real life, when you want to jump high, you would like to bend your legs and then extend them out to get a good jump. you can do the same thing by adding that bending down animation THEN extend your legs out. This gives a better realism and the figure of that character actually jumping.

For the "Fall" animation, I would just run that animation right after the character ended the "Jump" animation. When I would think of a fall animation, I would imagine that the arms are either almost extended out or making a 90 degree "L" shape and waving them kind of up and down very slightly.

Finally for the "Land", just do the same thing as the jump animation except go backwards.

This is a simple concept but really difficult to give a good realism to get it look right to the players.

http://www.youtube.com/watch?v=1nr_nVtScuc

Check out WoW's animations out and use that as a reference. Also, never hurt to record yourself jumping and use that as a reference. The Keyword is "REFERENCE" ;]

Good Luck!