Perfect tutorial RobynsVeil. :)

Like SteveJax said there are of course exceptions. But that's best left to the individual clothing, information that should be in the readme file. If the maker has found a certain collision offset to work best, it's good to mention that.  Some clothes require a different starting pose, others may need some draping frames before the simulation. At other times some scaling or adjustments in the starting frames are needed for certain effects too.

I also found that sometimes you want to change simulation values and other things, if the character moves into a different pose. Or you just need more frames, like for a figure that moves down to lay down on the ground. 

I think your sitting pose looks fine. It looks as good as it gets for me. The weird folds at her waist is the very topic of another thread here. 

If you are animating, they are hard to deal with, but for still images, I can often get rid of them by running the smoothing tool over them. 

Btw, really nice conversion. I have done quite a few conversions of conforming clothes too, with varying degrees of success, lol!