okay, the Magic Bullet on sim parameters.

It's not a bullet but a process, and it's not magic because some parameters (Offset and Depth) have practical upper and lower limits depending on the scene and animation itself. Which ones, why the process works and more details will be in the tutorial. Anyway:

Collision Offset: start with real world values, and visual requirements on the end result. Offset creates some distance between the body and the cloth, suggesting some thickness. I would suggest: 0.25 for lingerie and fine clothing, 0.5 for sweaters, 1.0 for thick cloth over cars and statues, 2.0 for serious winter overcoats.
Changing the offset does not affect system resources (the offset iself does, but its the same for all values).

Collison Depth: start with about the Offset value.

When the sim goes wild, then check the "object vertex against cloth poly" option first. If not good enough, then check the "object polu against cloth poly" option too. This will increase calculation time. If still not good enough, double the Depth and eventually, double again. This will increase calculation time even more.

If still not good enough, start doubling Steps per frame and go on doing so till the sim runs fine. Actually this IS the magic bullet, but the price is high: each doubling also doubles calculation time. This is why it's better to try the other options first.
This setting refines the sim from 60 steps per second (30 fps * 2 steps per frame) to 1,000,000 steps per second (30 fps * 33333 steps per frame). Which takes over 16,000 as much time. Pray you don't need to go that far.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though