Dispatchgirl, Here is a video from Leah Day which helped solve my problem with cutting crooked strips.
http://www.youtube.com/watch?v=EcpzwJMVTbc
You really have to make sure that folded area is lying correctly or the crooked strips will show their ugly face. Hope this helps you.
Oh, and welcome to the QB. It's a great place to ask for help.
edited: Looks like I was typing as Sewnoma was posting. That video basically shows what she is describing.