Knowing when and how to say no is really hard especially when you're a people pleaser. I'd love to see more written on this. 

I agree with Randi Zuckerberg that hand written thank you notes are good.

Have you ever sent someone a gift or did someone a favor and never received a thank you for it? We’ve all been there. It sucks. You know what’s even ruder than sending a waste-of-space-thank-you text message? Not saying thank you at all.

One of my favorite things to do, if someone really goes above and beyond the call of duty for me, is to send them a handwritten thank you note. Yes, I know. It’s old-fashioned. Retro, I prefer. But according to this Times article, maybe I shouldn’t bother? After all, my token of appreciation will cost the recipient an entire 30 seconds to open the envelope (the horror!), and read the note!

I did go back and read the original article Randi was ranting about:

http://bits.blogs.nytimes.com/2013/03/10/etiquette-redefined-in-the-digital-age/

It's not a bad article. It basically tells us to have empathy and consider other peoples' time.