Consistent camera settings are a good beginning for continuous looking footage. Here below I will try to explain how to achieve consistent brightness and colour of footage.
Assuming that the lighting of the scene stays the same, you can pick a shutter speed, aperture and ISO that gives you a desired exposure. If in the next recording you will use the same settings on the same scene the brightness of the image will stay the same.
It gets trickier when the light changes. By using your exposure meter you can get close to consistent footage. If for example in scene 1 your exposure meter shows -2/3 with the desired settings, try to get an exposure of -2/3 in scene 2 with the same metering mode.
This will only work when the scenes are lighted similar to each other. Night/day shots or inside/outside shots are not going to get consistent brightness ever.
Later in post-processing you can of course alter the brightness of two different clips, but you don't have much working space getting it right in camera is the best starting point.
Again assuming that the scene lighting stays the same, you can pick the white balance. On a GH1 this can be done in several different ways, it even allows you to set the colour temperature in Kelvin. Pick a method of your liking, but to avoid Automatic White-Balance (AWB). AWB is a big cause for changing colours across different clips because it can get thrown off easily by changing objects in the scene.
Baseline: for the same scene, set the white-balance manually and don't let AWB decide for you.
Again, in post-processing you will probably need to do some colour grading and this gives you the chance to colour correct your footage.
But, get it right in camera and you will save yourself some work.