The Keys to Thank You's

The first question to address is "When do I send a thank you card?"  Frankly, don't worry about the exact etiquette.  Anytime you think "Gee, I wonder if I should send her a thank you card..." you should do it!  With minimal cost and a little bit of effort, you'll build your reputation as a thoughtful person and make others feel good (which is really the most important part).
 
Tips for Personal Thank You Notes

1. First and foremost, buy thank you cards that are attractive and appropriate for the occasion.  Cheap cards can be just as cute as very expensive ones, so don't worry about a price point (most people throw thank you's in the trash - or hopefully recycling bin - anyway).  I like to stock up from the dollar bins at Target, Michael's, and JoAnn's Fabric.  I have an assortment of whimsical and classy designs.  It's easiest to get them out in a timely manner when you already have them on hand. 
2. Put your name and address on the top left of the envelope.  This way, the recipient now has your address and can add you to her (iPhone) address book.  Also, when you receive cards, you can tear off this return address, tape into a notebook, and refer to it for your own correspondence.  Also, address the envelope in your own handwriting, not printed labels.  Personalization is the key to making people feel special, as opposed to just another name on a list.
3. Address the recipient with "Dear" if you feel comfortable doing so, but always include the name(s) at the start.  You can also use a "Hello!" to make it sound friendly, but not too personal. Whatever you do, don't make the introduction and first sentence too generic.  It doesn't make a good first impression.  I try to make every thank you card a little bit different.
4. Continue on with a specific thank you for the gift, their attendance, etc. and perhaps share how you have been enjoying the gift.  This will not only make the gift giver feel that she got her money's worth, but let's face it, she'll probably keep getting you good gifts!
5. Personally, I think the thank you card should be quick.  If you haven't seen the recipient in a while, write a letter later sharing news.  Right now, focus on their generosity (not your new job or baby).  Also, it's a nice touch to add how well-dressed or lovely someone looked at a party (but only write it if you mean it!).
6. Leave a good last impression as well!  Thank the recipient again and offer your excitement about the next chance you'll have to get together.  Everyone loves to feel their presence is missed.
7. Now for the sign off.  I like to write "Much Love" to my close friends, "Love" for family, and occasionally I'll throw in a "Godspeed" to be cheeky.  As for acquaintances, I think a "Very sincerely" or "With gratitude" is a nice way to end a note.  A plain "Sincerely" is boring.  I suggest finding your special sign off and sticking to it!

Keep in mind that following a few guidelines does not make your thank you less sincere.  Always write from the heart.  If you've got a friend who gives you presents that are not your taste, I'm sure there's a little silver lining in that cloud somewhere!   You can always reference her generosity but not the gift.  Most importantly, don't lie about loving something that you don't (you'll either end up with more of the same or offend that person when she notices her present no longer resides in your house).  This is nearly always applicable to old people or folks at work who have no idea what you do on the weekends. But remember, they still showed up with something wrapped, and that deserves some gratitude.

Much love and Godspeed,
Taryn