Reminds me off the (travel) backpacking rule: Take all the stuff you want to carry and stick it in a pile. Throw half of it away. Look at the new pile in a few days and proceed to throw half of that away too. Works good.

Biggest thing to me is bringing too many spare parts. I carried an extra pound or 2 on my last tour for 5 months and didn't use a single piece of it.