Everyone knows that while you are a graduate student you are in a training program. I think that people tend to forget that a postdoctoral position is also supposed to be a training position. Often people use this to branch into new research areas, or expand their technical skills. However, some like the comfort of their postdoctoral positions and stay in the same lab for a prolonged time period.

The induction of new rules for institutions will ensure that the turnover of postdocs continues as their funding or tenure at the institution has a time limit. In these new times, it has therefore become pertinent to have an effective postdoc.
I believe the most important decision is choosing the correct laboratory to join. If the mentor is absent, on sabbatical, or has a large lab, you may not be given the help and advice necessary for success. Once you have chosen your mentor, ensure you communicate often and openly with them. You are both responsible for your continued development as a scientist and should hopefully work together as a team.
Ensure that the project is going to plan, and that they are aware of future research directions. Be accountable for your research successes and failures, and accomplish expected tasks such as publishing papers and presenting at conferences.
If there are other role models around you admire then it is acceptable to have multiple mentors. The advice you receive from each mentor will probably be different therefore you can get varying perspectives on topics. If you wish to have some autonomy, you can apply for your own funding. This not only looks great on your CV, but it may also give you some negotiating power as to the direction of your research.
Try to have a strategic plan, both for your research project and your professional development. Many institutions have a postdoctoral training office or postdoctoral association which will provide seminars for scientific and professional advice. If your institution does not have these, there are other organizations which can provide this training. For example, the National Postdoctoral Association (NPA) and Association for Women In Science (AWIS).
It is important to acknowledge that tenure-track positions are difficult to get, and the majority of researchers will not attain one. Therefore, it is vital to have a backup plan. The professional development you will have used with your strategic plan will be invaluable when it comes to Plan B as proof that you can perform outside an academic laboratory environment.
In these tough times, I do think it is necessary to say that we shouldn’t take a postdoctoral position if we don’t know what else to do. That hardly seems like a recipe for success for either you or the mentor. Approach your postdoc as the next key step in your career. However, all good things must come to an end, and we then need to move onto the next stage of our careers.