Just thought I'd weigh in on the "do someone elses" vs "create your own" routine issue. I had a long debate about this with Whit Haydn, and after disagreeing with him in print elsewhere, I have to confess that I have been won over to his point of view.
When you are getting started- learn someone else's published routine. Not only do you know what it is supposed to look like when you do it right, it has all the "bits" and jokes already built in. When you are performing it, you can then make little changes to make it fit your personality. That is when you will discover what about the way it is put together makes the routine work. There is probably a reason the magician tells a joke at a certain point, or makes a gesture. You may not know why until you are performing the routine regularly.
Take advantage of the work other people have done and published! Learn from their experience. You don't have to reinvent everything. :)
And about picking material- I tend to perform what I like to watch. Think about what pieces you have seen that you like, and why you like them. That always helps me pick material.