Here is what I have found that works for me.
My family and I have about 6-10 must watch shows per week, according to what reality shows are in season, and whether or not our favorite other shows are showing re-runs or not.
I have a tape dedicated to each show, and have it labled. When that show comes on, I pop in that tape and set the recorder. Then later, when I want to watch a particular show that I missed, I know which tape it is on!
There are certain shows that I never tape over, like Survivor and TAR. When that tape gets full, I just start a new one, and lable it Part 2!