What not to do in my store:
Call out, "EXCUSE ME!" across half the store like you're calling your dog. You could obviously see me, it wasn't like you couldn't find anyone. How about coming to within 6 feet of me to calmly and quietly say, "Excuse me, I need some help."
I thought the "EXCUSE ME!" lady was bad, but I had an even worse customer after that (not the same day). This customer wasn't just rude, she was also old and had the "I'm a queen" complex. "Hey lady!" I turned towards the voice as I continued walking to the front. "Yeah, you! Come over here right now! I need some help!" I replied, "I'll be with you in a minute once I see what my cashier needs!" Luckily another employee heard her (actually, EVERYONE in the store must have heard her) and the other employee helped her before I finished in the front. Good thing, too--I don't know how polite I would have been to someone who shouts at me like that.