LeBlanc has the highest AD for ranged champions, making it easier to farm with her compared to other midlane mages. Use DISTORTION to farm when you can but beware of the mana cost because of you use it too often, it will drain your mana bar really fast. I suggest only using DISTORTION to farm when you can get three or more minions. Other than that just farm with your autos for the most part and save DISTORTION for poke.

POKE COMBOS (Used only for poke, not all-in)
Poke 1:Q,W.AA
Poke 2:E,Q,W,AA
POKE 3:W,AA
KILL COMBOS (Used for assassinating your lane opponent)
Kill 1:Q,R,W,E(Only if needed)
Kill 2:E,Q,R,W
Kill 3:W,Q,R,E

Those are the basic combos that are essential to learning LeBlanc. The poke combos should be used on her powerspikes and the kill combos are for mid game when she can roam and just 100-0 the adc or midlaner.