So I have been playing with Premiere Elements 8 but I have still have a longs way to go.
I realize what would really help me improve is to examine the workflow of others and implement what they
have used .
Here is my baseline.
I have footage from a Canon HF 200. I have used http://www.koyotesoft.com/ to convert my AVCHD files to MP4.
Describe what your workflow in order to get this footage so that it runs properly on Premiere Elements 8.
This can go so many different ways I'm not sure where to begin, outlaw! My books take you through some basic workflows -- but even then you're dealing with half a dozen different media sources and camcorder types, the challenges and liabilities of each and what the smartest way is to deal with each media type. So, unless someone has a camcorder exactly like yours and a system set up exactly like yours, you may be hard-pressed to find someone with exactly the same workflow.
You say, for instance, that you're converting your video files to MP4. Well, for most users, an MP4 (unless it's set up with standard AVCHD specs) is going to cause problems for Premiere Elements. Yours might be the exception. Have you been able to successfully go from capturing your video to project to DVD and gotten great results? The multitude of possible codecs, frame rates and interlacing issues make it quite likely that you will have problems.
But the short answer to your question? If you're going to edit in standard video, use DV-AVIs whenever possible for your source files. If you're going to work in hi-def with plans to output a BluRay disc, use hi-def MPEG2s as your source files. You'll know you're using the ideal format if, when you place your clips on the timeline, there is no red or green line above them.
Though, as we often say, your mileage may vary...