This build is great for aggressive playing. Harass whenever you can, attack at any chance given, but remember to save mana at the same time, considering that Miss Fortune runs out of mana fast.
Double up
You'll only need this to attack the opponent from a safe distance. You'll probably rarely use this.
Impure shots
Feel free to max this simultaneously with make it rain. Use this right after you "e" or when you're destroying turrets.
Make it rain
I just max this out first because I like having more time to graze bullets in my opponents. I also like it when my opponents can't escape.

Until you start rampaging, do last hits only. Let the opponents push.

It will help a lot until you're just dominating the other team and fed. After that, you can take on many champions 1v5.