My general sense is with pinhole it's better to err on the side of over exposure -- easier to have to draw out the print making exposure than have no shadow detail on the negative.
I still guesstimate. I'm more of a "just give me a camera and I'll shoot and see what I get." Sometimes, it's a total failure. Sometimes, I get a roll of happy accidents. Sometimes, it's a 50/50 coin toss with what I get. I'm mostly happy with my results.
I love the smell of fixer in the morning...It smells like...PHOTOGRAPHY!
The photo blog has moved... I Love Film : by Susan McNutt, the mad photographer