Step 1: Takedowns
And simply, for me actually, i find taking the one who is bothering you to the ground rather than executing strikes is MUCH easier. And if you practice these at home, try not to really slam your partner to the ground, just enough to get the feel for it. And also, sometimes you dont even have to stun your opponent to execute the throw, if you just do it very fast.
Now another there is a video for, the clinch. When in the locker room, most importantly, if there isnt a teacher around, clinch them. Such as if they trying to whip you with a towel, moving very close very quickly and clinching them, then throwing them i find is the best option. And once they are on the ground, you can then take the towel from them, and whip them while they're on the ground.
I find these are very easy to perform on a very untrained opponent, simply because, they do not know what to do, and since most school's students dont have classes in a martial art, its very very very unlikely they do.
And then i find THE easiest thing to do when they aggravate you in class or so, is a wrist lock. I find this to be the EASIEST thing to do to make someone give something back. I find the supinating wristlock is the easiest to perform. Such as, once at school, someone took my pencil pouch from my book bag. I turned around, grabbed the wrist on the arm that was holding the pencil pouch, and wrist locked him. I had him wanting to give it back within a split second. It is shown in the second picture, and here is the link to the wikipedia article for wrist locks.
You may also wish to look at a list of grappling holds on wikipedia, the ones used in the video are the collar tie and underhook. Here is the link for the list of grappling holds.
I have found some army tactics to help with this. Here is the link, however keep looking at this instructable before you go to the page.Army Tactics
Let's say your opponent strikes you with a right punch, which they usually will, due to many people being right handed. You can then parry to the inside and strike the throat, face, or solar plexus(as in the picture), then you can execute the throw.
And the second throw i dont have a picture for, I have used this when I have a bookbag on and cannot bring my opponent onto my hip or back, the double leg takedown. This one also has a video.