I don't know what element I would go with. So instead, I'll list what I'd try to do with each!
With firebending, I would probably make a lot of things out of metal by carving out molds and melting the metal so I can pour it in, and also to start up blast furnaces. And if i could use lightning too, I would go arounding making weird electrical effects, like Saint Elmo's fire. I would also use my abilitys to power various engine, if I had them.
With earthbending, I would buld and/or tunnel out a building to make into a fortress/workshop/labyrynth/whatever, and also a set of stone dolls that I would use in a puppet theatre. And according to the Wiki on the show, you can also do magetic stuff with earthbending, which I would of course use to stick things to other things.
With waterbending, I would power hydrolic devices, and to put myself into stasis so I could go to THE WORLD OF TOMORROW. Also snowball making.
With airbending, I would power windmills and boats, and to hold a blanket over me as a form of shade, to float away whenever I wanted to leave, and generaly to be aloof and lazy. Also, I would give myself a beach bum accent for absolutley no reason whatsoever.
But no matter what, I would use my bending powers to pull annoying pranks, like taking out the glass in a window and replacing it with ice, so they'll be like "Wait why is my window melting?". CALL ME THE TRICKSTAVATAR.