Pro tip: your mark is always wanting to do something different than what they’re doing now, even if that’s as simple as waiting for a pass to be thrown.
A little bit extra: you are never in a good place as a one-on-one defender. Constantly re-evaluate, reassess, and reposition. Do it well and your mark will also never be comfortable even if they successfully receive a pass every so often. Make sure if they receive the disc they get it in a place you are conformable with rather than a place they are comfortable with.