One of my previous coworkers went from working in an engineering research lab to a clinical research associate position. He was only a year or two into his career so the transition to the next job was a big step away from their current role. From what they had mentioned to me, there really is nothing like on the job experience where you apply your ability to learn and grow within that role rather than preparing yourself for that type of position. If one were to gain a position that would require experience, I would suggest just fully understanding the phases of a clinical trial for that device or medication as well as understanding what the company's products are that would need extra care. From an experience perspective, one should have the knowledge of that field and the ability to converse well with others as some positions are borderline auditors that need to be able communicate their thoughts to their client on patient affecting trials. 

Transitioning from R&D into clinical research or vice versa should be a smooth transition since both careers involve a research study, business insight, developing new products/treatments to improve existing methods, designing trials, setting up studies, and writing up reports. Anyone who is looking to switch career fields should do research in the field of interest and see if there is any overlap in the work they currently do. They should also find the position of interest, try to find the hiring manager for that position and set up a meeting to express interest and see how your current experience can be of benefit for the new position.

As @wmckennedy@msm.edu stated, moving back and forth from clinical research to academic research should be quite easy as they are both related and interconnected fields. Regardless of what research field you are in, the expectations of how one should think, solve problems, and conduct research is similar. At the end of the day everyone in research is trying to answer the unanswered question and its a collective effort to reach that goal. I personally have been working in academic research for almost 2 years and am now preparing to enter the clinical research industry. I noticed through my application process, that I am applying to jobs that are catered towards research and development specifically in drug development and there are some skills that seem to be common across the board whether you are in academic or industry research. Some of these skills include microscope abilities, immunohistochemistry, western blotting, and stereology. These are a few skills that I have personally come across when I am specifically looking for RnD roles in Drug Discovery and Development and I feel that having a background understanding in these different skills can be beneficial to anyone transitioning from industry to academia or vice versa. Furthermore, I am not entirely familiar with how data acquisition differs from academic to industry research, however, I can speak on my academic research experience with statistics. I have personally used GraphPad Prism and Excel to conduct statistical analyses. I have primarily utilized paired and unpaired t tests and ANOVA testing to identify trends and changes between groups based upon specific variables that are being tested for.

I have actually been looking into a role doing data analysis in a clinical research environment. Many of the roles I have seen are for clinical data managers. From what I have seen the important skills there are mostly SAS knowledge. In terms of projects it should showcase your ability to clean and organize data.

One of my professors told me that graduate students can volunteer on a Institutional Review Board (IRB). I don't know of any clinical trials that NJIT is performing, but Rutgers University Hospital (NJMS) actively performs clinical trials. This is in line with the on-the-job experience that jaf22 mentioned. Alternatively, a stint in the FDA can greatly improve your credibility as a candidate to prospective employers.