Final answer:
The most important aspect of writing a letter to a colleague with whom Jim has worked for 12 years is to maintain a professional and friendly tone. Specific examples of projects or accomplishments should be included, along with expressing gratitude and acknowledging the shared history and camaraderie.
Step-by-step explanation:
The most important aspect of writing a letter to a colleague with whom Jim has worked for 12 years is to maintain a professional and friendly tone. Jim can express his gratitude for their collaboration and highlight some of the valuable experiences they shared together.
Jim should also include specific examples of projects or accomplishments they achieved as a team, which demonstrates the positive impact their working relationship had. Additionally, Jim can mention how much he values his colleague's expertise and contributions to their shared work.
Overall, writing a letter that acknowledges the history and camaraderie built over 12 years will make it meaningful and memorable.