How to play lulu mid ad against assasins?

I've recently went against an akali with lulu mid ad, I did pretty well during early game...until she hit 6. It was my 4th time playing lulu since I bought her so I didn't know her limits and got killed multiple times running away not even thinking to attack with autos...Should I have gone in and attacked and Should I go ap or ad against assassins like akali and kat? Would there be a certain combo I need to use against them? I know lulu's w cancels kat's ult... What else? Any tips for laning phase and who I should shut down early?