Baking with the Cake Boss by Buddy Valastro. It's very good; a baking apprenticeship in book form. Buddy writes that piping cookies, lots of cookies, is the best way to develop your piping skills. He also specifically recommends a canvas piping bag for piping cookies as it is strong enough to not split, so I bought one. Sadly, I forgot to get almond paste, which is necessary for Buddy's cookie recipe.
A note about piping. It isn't nearly as hard as you think, and it's very impressive and a lot of fun. I highly recommend Wilton's Decorating Basics class, which is offered at Joann's and Michaels's. However, if you don't have the money for the class (which cost me about $100 total, with supplies), I recommend using the tutorials on YouTube. This is how Wilton actually trains its teachers.
My hands were hurting last night, so I decided to try the Butter Cookie recipe from ATK's Family Baking Book (I love this book).
open star tip, I'm guessing an 8B or 6B? I used a 1M tip, which has fewer points and is also used for drop flowers. You can use any tip that is large enough.
Onto the cookies. It's a pretty good recipe. When I first tasted them, I though "OK but boring; would be better with almonds." However, I then ate a very, very, embarrassingly large number of them. My husband liked the cookies too. I think I'll keep playing with the recipe though.