Thank you is one of those words (technically a phrase) that everyone should know and that everyone should use as often as possible. It's one of those words that can make you look like a southern belle (or beau) or turn you into a ass-extraordinaire, too. Like most English, it's quite versatile.
You never know when saying a simple "Thanks" could just make someone's day completely. There are so many people out there who do not get thanked that I'm sure they wonder if anything they do is even getting noticed. And because we're all striving to make ourselves look as good as possible to promote ourselves, I think that us author-hopefuls should say Thank You to just about anyone and everyone.
My French Professor told me one day after class--because I was the slowest to pack up--that she loved to teach and she quite liked living in the US, but the one thing she could not get over after living here for 20 something years was the fact that students, and really a lot of other people, are so rude compared to the people she knew in France. No one said please, or thank you or anything else. Never been to France, so I really don't know if that's true, but I do know that American teens (cause that's who she deals with most) are definitely not the type to thank her for teaching.
On another note, how many of you have/have read the type of story that utilizes the Taciturn-Man? (Sometimes woman.) I used to be an avid manga reader and they use taciturn (or tsundere, as they call it) characters all the time. And most of the time they're pretty fun. I've written quite a few characters like that myself. But, are they really likable? If they're true to the meaning of the word, are they really going to be relateable, likable--or even lovable?
Thanks for reading! :P