We may have to decide on weather we need to approach the problem at hand using Six Sigma Methodologies. Here are some hints Which are generally accepted project identification guidelines which can really fit into  Six Sigma.
Any project should have identifiable process inputs and outputs.
A good six sigma project should never have a pre-determined solution.  If you already know the answer, then just go fix it!
For projects that have operator or operator training as an input, focus on ways to reduce operator variation, thereby making your process more robust to different or untrained operators.
All projects need to be approached from the perspective of understanding the variation in process inputs, controlling them, and eliminating the defects. 
If you are using the Secondary data validate the data first. If you are not confident of the authenticity or integrity of the data, it is better to recollect the data.
You should have enough data to start with. If you do not have data or it takes too long to collect the data look for alternates. About 30-40 data points minimum in a month is ideal. 
The team should be committed to the improvement project.
Sponsor should see the measurable benefits to have the support.
If geographical separation within the team is there, then finding a workable solution before start of the project. In fact many projects fail due to this constraint.