I previously posted about Whale Hunting: when startups seek a landmark deal with a big company. For those who are lucky enough to harpoon such a whale, now comes the hard part... as there are any number of things that can go wrong in the years to come. Here's a recent example I encountered:Our biggest customer represents almost 50% of revenue. Our champion at the company is an executive who has been happy with our product for two years. Unfortunately, just before signing our renewal, he got fired. The renewal is due in a few weeks and we haven't yet met his successor.Yikes. While there are no easy answers to this immediate problem, we can do some things to improve our odds over the long term.