A while back I blogged about using Checklists, but there's another task you want to incorporate into your workflow - documentation.
Now, I'm not just talking about documenting the logic, system flow and data and structure changes, I'm also talking about documenting your daily activities (commonly referred to as a journal.) It's amazing how useful a private journal can be when you need to revisit the thought process you went through to develop the processes you're implementing.
I'm also talking about creating summary reports - even if they're only going in your own files - detailing how the implementation of a project went, the successes and failures, the unforeseen issues that came up, and even the political reactions, if they occurred. (It's good to be able to go back and later refer to who helped and who didn't.)
Lastly, you should create a form of incident report any time any issue arises. Even if it was a minor issue, not necessarily related to work you'd done, it's good to have a record of the problem, the perceived problem (they're not always the same), the resolution, and any thoughts on how the problem could have been avoided or prevented.
When you've got this kind of documentation, you'll be able to answer any critics, even well after the real issues have been long ago resolved.