It's always good to ask a woman for her opinion about something, why not about what color shirt looks good on you?
Here's an idea, give her a like like "Hey, you look like a woman with pretty good fashion sense (half zing/half complement), come here and give me your opinion on this..." This gives you the opportunity to get her away from the register and off to yourself. If she says that she has to watch the register, call over another salesperson. Say something like "Would you mind watching the register for a couple of minutes while... ummm, what is your name, oh Sheila, while Sheila helps me for a bit." You've just zinged her, complemented her, showed her that you can be both forceful and gentlemanly PLUS you got her name, easy isn't it?
Once you're at the shirts, just tell her a little about the event and let her go through her sales spiel. Remember not to choose something just because she says it looks good, you don't want to come off as a wimp. Let her know that you have your own taste too.
After just a couple of minutes make your decision on which to buy. If she's a good salesperson it'll be one that she had shown you. Say that you're choosing it because whatever (fill in the blank). Make sure the reason is one that she had said when initially showing you the shirt but say it like you thought of that reason by yourself. Then tell her that you appreciate her help and that you're going to take her out for coffee sometime. NOTE: You are GOING TO take her out for coffee, you command it. Then tell her to give you her home number so you can call her when you're free. There you go...
Damn, maybe I should write a book, what do 'ya think?
Happy sarging.....