First off, congrats!
Now let's see...
Ask the lady you are getting her from if she was socialized very much. Did the lady walk her around the neighborhood much? What about puppy classes when she was young? I'm giong to assume she didn't do too much of this (just for the sake of this post).
I would think about investing some time in an
adult beginners training class (obedience). Even if she knows the tricks, she will be able to socialize with other dogs in a controlled setting. Also, introduce her to your friends, and let your friends know to be very patient and soft-spoken with her at first. Practically ignore her until she can get more comfortable.
My friend adopted a chihuahua from a shelter that was about 5-7 years old, and exactly the same. Took a while to warm up to my friend at the shelter and was just very fearful overall. Over time (not too long), she warmed up to my friend and her family. However, to this day (and she's had the dog for about 5+ years), the dog is still very fearful and barks at anyone new until she's met them several times. Even with me, if I go to kiss her or something while she's sleeping, she'll nip at me out of her instincts.
Now, I'm not saying your dog will be this bad. Just saying to be prepared that the dog may never be the "take anywhere" kind. I doubt (again, for the sake of this post) that the lady took her many places. BUT, your dog could turn around with socialization. Hence, the classes and letting her meet your friends (while they are calm and quiet with her).
I hope this helps a little bit. Your vet can probably give you good advice, too. And ask the dog trainers at your local
pet shops. They may have some good advice, too!
Good luck, and congrats!
