Good slide design for teaching?
This morning I watched a video about how powerpoint is killing our ability to teach properly. It can be seen as a lesson in bad slide design. One key message is if you are reading your slides to the students, you are not teaching. Ultimately, slides should just contain key information, and you should tell the rest of the story. 

Regarding some of the other points: 
animation of text should be left to Walt Disney;  there should be one idea per slide (slides are free!);  separation slides are a good idea to let the listener know when topics have finished, which is especially helpful if the separation slides are blank (or even black!).

Less is more. If you want to give the students more, prepare a handout.