photopop wrote:
Then how do I set the slave if I can't measure it without another flash going off?
There are really a lot of ways to handle the the issues that you've been running into. It might be a good idea to study up on lighting and a great place to start is Strobist's Lighting 101....
http://strobist.blogspot.com/2006/03/lighting-101.html.
If your skin tones are blown out then it sounds like your exposure if off. Softer shadow transition will come from using a large apparent light source (bigger modifier and/or move it closer to the subject). As for measuring the fill, one way to go about that is to block the main light from hitting the subject. This way when you trip the main light it will still trigger the fill light but won't contribute to the exposure. Just let some of the light from the main bounce around the room and it should trip the slave. You might want to start by picking camera settings for the light that you can't adjust power on and then dial in your second light to taste. Also remember that you can decrease a light's power by moving it away from the subject (if you have room). Hope this is helpful.