I can't help you regarding school reputation management, since that is very tricky, and I didn't study in a US school. But, as far as countering general AA goes, I personally use the following strategies:
1. Remember this quote: "You miss 100% of the shots you don't take." - Wayne Gretzky
I tell myself that if I approach, I may at least be able to succeed 10% or 20%, if not get significant results. But, if I don't approach, the best I can get is 0% success.
2. Tell myself that if I don't approach the girl, I'll not be pushing my comfort zone. That means,I'll be stuck at where I am, and my day will be wasted. No improvement from where I was yesterday.
3. I remind myself that most girls NEVER have any guy approach them in their whole life in a grocery store or sidewalk. Even the most beautiful girls are not approached by guys, can you imagine that? So, I tell myself that even if she acts rude or bitchy, it is worth the effort, because I will have made her day. And you know what, most probably even after 10 or 20 years, the girl will remember that a guy appreciated her that way! Girls like the attention even when they don't show it.
4. I think of the worst case scenario. I ask myself, "Will she slap me if I go say hi to her?" The answer is always 'No'. When the answer is 'No', I force myself to mechanically approach, because nothing too bad is going to happen anyway!
5. Sometimes, I'll just not think of anything, and force myself to approach all girls who seem hot enough. The way I do it is ask myself "Do I like this girl's body enough to fuck her?" If the answer is "Yes", then I forcefully stop all negative thoughts and mechanically approach her.