Being dropped in the middle of a project that is already in a bad shape (over budget, over schedule and under compliance) is not easy (or funny). So try to make the best of it and get out of it alive.
On most cases, you get a project start with the business case or whatnot, then continue on with a chain of events. On most of my encounters I have dealt with projects already started and left in the Bermuda Triangle to drift or where the end was reached with no particular direction. The usual case of this type of situations comes from the mind-set of the culture the individuals are involved in. Regardless, you will have about no time for testing, little time for development and the who cares attitude. Not to mention you dont want to look stupid in front of the client going over to them and asking the questions that should've been asked beforehand.
Well this has been my case for the past 2 projects, they were already started, got derailed, no documentation whatsoever and an ever-present pressure to finish off because its already over budget. I can tell you now its not an easy task to come in SWAT Teamstyle and continue a project. So I made it... twice... with relative success, here are a few pointers.
Tip#1: Focus on goals and measurable outcomes not on reconstructing whatever happened
I met some friends who make extensive use of CIMOSA, which is a simple yet effective approach. I borrowed some of their knowledge, and decided to focus on the KPI's and CSF's (see Definitions section), that is derail from the temptation of reconstructing the past design and unmade documentation from virtually zero requirements documentation or whatsoever.
Tip #2: Make sure that you get your project manager in check with the tasks
I noticed that even if the requirements documentation was bad, dissecting the requirements into an Excel spreadsheet and then assigning the project tasks that related to that specific requirement worked wonders with only a 4 to 16 hour effort (time is porportional to size). So you can actually give intelligent feedback to the PM and focus on the result: compliance to contract.
Tip #3: As cruel as it sounds, stick to the contract
Yes, I HATE mediocre work, poor solution design and giving the client something I know that doesn't solve their pains. Yet, in all honesty, you are not going to solve that organizations problems in a week, or 2. It will take some extensive work that was previously undone and HAS to be performed in order to really attack the root causes of problems, otherwise, you can and will possibly transfer the problems from functional organizational unit, or make it worse. So make sure to meet contracted demands in due time.
Tip #4: Dont forget to write it though
Even if you cant solve all of an organizations problems and need to focus on the task at hand, make sure to write all this stuff up. Bring it up at an internal status meeting and make sure your sales people get a hold of this information. If you can forsee substantial business improvement within your client's operation, he will appreciate you taking the initiative and bringing up intelligent assessments (and possible HR investment from your company to further analyze this and make a business case).
KPI = Key Performance Indicator - measurable outcomes of a specific process that can tell you if you are headed in the right direction
CSF = Critical Success Factors - business goals that have to be met in order to comply with the business needs