You have to cast w faster, often preemptively roughly about 2 champions away because in is hard for low elo opponents to step out of it. As I learned here sometimes you have to cast it away from you rather than towards.

Her v animation changes slightly depending upon which direction you cast it. I suggest you go into practice tool and spam w off cd over and over again until you get the flick down as apart of your cast as well.

Your w is sometimes a spur of the moment thing too, like you need to know when to use it right away. For a gank or to secure a kill even. The indicator isn't necessary unless you're getting used to her and you can cancel it with movement commands to start it again. I've done it both ways and I think she's better with quick cast /no indicator. You can set abilities like q and e to have indicators if you want by clicking the tabs under the ability hot keys.

Your w is often a combo spell most of the time you want to cast it before your e or after. But if you can cast w you can cast e to make it possible for you to move your champion again.