Greetings Ninja,

The way i do it with Morgana is, i wait a few with the q unless they initiate.
Look at their movement when i move up etc, then aim just a bit ahead of them where you estimate where they will go to.
Thresh you can aim on the player especially if you land the slow, this one you have to aim for where you think they will go.

Not far ahead but just next to the champ.

So, just move in a few times and shoot a q.. 2 or 3 times and see how they adept to it.
Remember that and use that to your advantage after that.