Stealth is the key here.
Begin by keeping an eye on the potential target.
If caught watching, look away and fake disinterest.
Continue to fake disinterest so as not to raise any interest by the humans to remove said target.
When in doubt, give the "What? I'm not doing anything" look.
Then, when it seems safe, move in slowly, and.......
Yep, it pays to be smart. I hope you have all learned something from this lesson.