The answer is easy - rank the activities by money made or saved. The really hard problem is the ranking as you don't normally have the perfect information that

The answer is easy - rank the activities by money made or saved. The really hard problem is the ranking as you don't normally have the perfect information that allows you to calculate the exact dollar value of any change. More usefully I use two rules. 1. Fix all bugs now. The software should do what it claims to do. If I can't fix a bug (rare) then stop claiming the software does whatever the bug prevents working as a feature. 2. Once 1 is taken care of then work on those things that will bring in the greatest long term value first. I have to say that I mostly do this by feel as I have no good way to get accurate information out of my customers - they often don't know what they want until they see it.