Weigh every item you are carrying and list them in spreadsheet. Go over the list and eliminate as much as you can especially noting heavier items.

It's best not to carry anything that you "think you might need". Only carry things you know you need. If your not sure you're best off leaving it at home. Second best option is to mail it home after a few days into your tour and you haven't used or really needed it.

edit: just saw Carbon wrote the same thing about spreadsheets. +1 on his post. Do it --> it works.