The following is a list of some “big dos.” Just flip things around to answer your question.
1) The project targets only one CTQ (for purposes of improvement).
2) The target CTQ should be measurable – conveniently and economically so.
3) The CTQ should have a well-defined set of performance standards.
4) The CTQ should not involve destructive testing or excessive preparation.
5) The CTQ can be readily linked to some form of value.
6) The project must be “complete-able” and “conclude-able.”
7) The CTQ and related CTP’s must have a clear line-of-sight connection.
8) The underlying process must not cut across organizational boundaries.
9) The CTP’s must be capable of being manipulated or otherwise altered.
10) The process owner must set aside committed resources for the project.
11) The Black Belt must be given autonomous control over those dedicated resources.
12) The nature of the project must “match” the nature of the curriculum.
13) The project should be consistent with the Black Belt’s professional experience.
14) The Black Belt must have open access to the instructor during project execution.
15) The Black Belt (and instructor) must be a part of the project selection process.
Get these things right, and it is doubtful you will fail.