Hi Weaver, I sympathize because I have a hard time reading those color gradients as well. These are not silly questions at all.
GH and KH are actually the easier tests to read (compared to the others where you use the color cards). After getting a hint of yellow, I usually get to a solid yellow when I add one more drop. I would just take the reading as between the two. For example, if I get a shade of yellow after 7 drops and a solid yellow after 8, I would estimate it as 7.5. You can also use the 10 ml method suggested by bigstick to give you a more accurate reading if desired.
When looking through the test tube, do it from the side, not down into the tube. When using the color cards (e.g., for ammonia, nitrite, nitrate, etc.), hold the test tube right up against the card. If there's any gap between the tube and the card, the color looks a little different (due to light coming from behind the test tube).
You may already know this, but I find it a bit easier to read the color cards under fluorescent lighting as opposed to incandescent.
Hope this helps.