I recently posted something similar on my end user connection for mid-market companies on BeyeConnect. But as I've been doing some research and working on a general market landscape report, interviewing companies using BI, etc. I am starting to see some trends in relation to how organizations would do things differently if they had it to do over again.
So far, the three things I've heard most in terms of how organizations would do things differently, or in other words, general lessons learned, are as follows:
1. generating buy-in beforehand because, in many cases, it is difficult to gain adoption when end users aren't involved in the process (whether because they feel they are being forced to use a new solution or don't trust the data, etc.)
2. training and whether to take advantage of formal training or spend time learning the solution(s) independently
3. not understanding the full breadth of functionality beforehand, thereby spending a lot of time tweaking reports and metrics identification (in some cases, this also relates to the collection of business requirements as well)