Part of the Problem

These two photos illustrate a large part of the problems I'm having with glazing - visualizing the final result.  You can see how different the colors of the raw glaze (first photo) and the fired glaze (second photo) are.  The two pieces in the second photo are the right and lower pieces in the first photo which is a shot inside the kiln just before I fired them.

And it's not just the colors.  Some glazes are opaque, some transparent, some glossy, and some matte. Some are speckled and some aren't.   Huh?  How are you supposed to keep that straight?  My only guess at the answer is "practice."

The other parts of the challenge are that you only get one chance - there's no "painting over."  And you can't get rid of mistakes very easily - if at all.  Once the glaze is on the bisque ware it's very difficult to remove, even with lots of water.