Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Just a basic guide I use for LeBlanc, only uploading to help a friend who just started playing her.
Start by harassing with Q and once you hit level 2 harass more with a Q+W combo, using the Q first and the W to silence and teleport back. I get a lot of first blood's with LeBlanc just because people don't see her doing that much burst at such a low level. Keep using that combo to harass in the beginning and if you still haven't got a kill once you hit level 6 that shouldn't be a problem. If you are using your ult at level 6 and you have been following my spell sequence than you should prioritize your ult to be Q.
Continue to sit in the back of team fights and teleport in and out when necessary, silencing those who need to be prioritized with silence of course. Constantly popping in and out with your teleport can put out some amazing CC and AoE damage while staying alive.
Just continue your mid game deal but at this point you should have a lot of stacks and a lot of ability power so you can solo a lot of champions if you get the silence off. Be careful around 2v1 fights though, if you're doing well you can take them both most of the time unless they have a CC.