One tip on lighting. They didn't teach me this in school I had to learn it. If the light is moved to the rear of the person it reflects off the object and increases it's exposure.
for example if I take a light and it's in front or slightly to the side such as a typical portrait lighting. If I take an incident light reading and set the camera accordingly that exposure would be correct. Lets say the camera is 12 oclock. If I move that light from 12 to about 3 and keep the distance the same the exposure is the same.
Now I move that light to 4 oclock it will look over exposed even though I didn't change the distance. It will get even brighter as I get closer to the camera axis such as 5 oclock. I burned out a lot of hair when first learning to do portraits because I didn't understand this.
I now use it my advantage to gain extra power from a light or to shape an object with a highlight.
I try to keep this in mind when shooting receptions if I have lights in fixed position in the room. I'll set them so my base exposure is F8 and know that if the light gets behind them it will give a sort of highlight that I can either use as is or stop down to get the correct exposure for that particular light.
I hope that makes sense. It could be why you get strange exposures while using a light meter.