I have read a lot about what the FZ's histogram feature does (researched on this site and others like Luminous Landscape). However, I can't seem to find practical advice about which settings to adjust based on a histogram reading.

Please review my example below and tell me if I'm on the right track or if I am missing something.
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Example:

1. While in aperture priority mode, I have the histogram displayed. It shows an even distribution of lines (lines appear from left to right).

2. When I press the shutter half way to focus, the histogram changes. Now the lines are way over to the left (black tones). Why the change after I press the shutter? I assume its b/c the camera determined the exposure based on my current settings---which then affected the histogram. Right?

3. I realize I need to make some adjustments or the photo will be badly underexposed? But I'm not sure what settings to adjust? I try exposure compensation (+2) first. It helps a little...the result is more bars appear to the right now....but not enough.

4. I then change the aperture value to 3.3...to let more light in. This helps. More bars appear to the right. But its still skewed to the left side of the histogram.

5. So I adjust the flash output (+2). This seems to make the histogram more evenly distributed.

6. So now i can take the picture with some confidence that it will be exposed well.

So am I on the right track here. Basically, I'm trying adjust my settings based on what the histogram tells me---tso that I get the correct exposure.