Twilight may not participate at sports, but she is a great hard working student, and I bet considering how strong her magic is, that training under Celestia was really really hard, I am sure she will do her best on RainbowDash lessons.
That's an interesting style; especially the color pallet.
Twilight looks cute when she's exhausted. I think it's because when she pushes herself really hard with either studying or manual labor, she really shouldn't be surprised when she needs to drop onto a cloud and rest.
Oh, Twilight... Such a dilemma: I really want you to sleep well, but the irresistible cuteness of a sleeping you makes me want to nuzzle you as well. The only thing that helps me now is that you're up on a cloud, so I can't reach you easily. Sleep well, my love, and don't fall down.
Indeed, Twilight will have a ways to go before she can fly as proficiently as other flight-capable ponies. I really like this hair, frazzled around the edges but still retaining its general shape. And it's some very pleasant lighting you have here, and some very fine-looking highlights in the hair. Her pose does communicate tiredness and resting, all of it, from her legs to her ear to her wing(s). Finally, that face... Those eyes with them eyelashes are wonderful, and the expression itself is, as said, irresistibly cute. Well done!