read the sticky on here Sacol about basal checks - it makes sense of something that is potentially vey confusing!
I followed the advice it gave and it's got my overnight basal PERFECT. I can now pretty much guarantee (unless I do something stupid of course!) that whatever reading i go to bed with, I'll wake up with it about 4.5-5.
and of course, the pumping insulin book, to explain how things all link into each other.
good luck!!