Mirana is one of my favorite Hero in DotA 2, i play her so much in the middle lane
I have decided to do this build for help someone players who wanted to play Mirana mid.
I expect this guide will be helpfull to play Mirana in middle lane.

First you have to take the leap in first spell because if you are ganked in the first lvl it will be a good escape against all possible situations !
After take the arrow and then the starstorm. Then you just up the starstorm and after you will alternate between arrow & leap. Your ultimate isnt really helpful in the early game, so skip it until the lvl 9/10.

On the lane don't be passive, try to harrass the maximum of your possibilities and try to deny too.
Try to take all the runes, it will be helpful for kill your opponent.
But your must possible way to kill your enemy will to try to arrow him ! If you touched him, move closer him and then use your starstorm because starstorm have this passif : The closest enemy unit to Mirana in a 425 radius will be struck a second time for 75% of the damage. And this is the most helpful way to shut down very fast the enemy before he countered you.