What these guys said is good advice... I personally started with the typical 0 deg back, +18 or so front that everybody in the early 90`s started with. Over time I played around and ended up at -12 +12, then within the last few years I`ve gone to -9 +9.
I started my GF out on a modified duck stance, -3 +15 or so to get her started, and she switched to -9 +9 this year and likes it. One look at the various stances the pros use, and you can tell that it is a VERY personal thing and there`s no right or wrong as long as you don`t blow out a knee!!!