I am working on it at the moment and almost have a handle on some of it, but here are some of the tips I DO have:

1. Read up on the idea of "constrained" cloth groups. It is important that shoulder straps and so on that "hold up" the clothing be in this group most of the time to keep it looking natural.
    
2. Set the number of "frames" for the cloth simulation low... like 3 until you get what you want. Often even though you are not working with an animation P5 will try and simulate for 30 frames.
    
3. Read up on "drape" frames.

Now, my questions:

When I clothify P4 clothing, often the abdominal grouping of the clothing will separate away from the upper part. The  cloth simulation will treat groupings as separate clothing items. I need a way to tell the cloth room to weld the seams of clothing groups - but keep them as material zones.

Any ideas?