Subject Matter Experts (SMEs as they are commonly called) are focused on the content and are not overly involved or interested in the other aspects of the training design. A SME is brought into the process to provide content knowledge and to ensure that the details are current and accurate.
The best SMEs are experts on the topic, and can also communicate the basics that someone new to the job needs to know. In addition, they are excited about being a SME.
You've found the perfect SME. She has all the experience you need. How to you ensure that the relationship is productive and positive? Start by providing a clear definition of roles and responsibilities. Who will do what? How? Provide clearly written objectives. When is it due?
Try to plan this together to begin to build a positive working relationship. Pay close attention to the SME's needs. Do your own homework, like learning the SMEs' terminology and the basic concepts. Be respectful of a SME's time. The more you can work around your SME's schedule, the better.
Communicate frequently with your SME. Keep the person informed and follow up regularly. Integrate the SME on your design team to build a shared feeling of commitment, accountability, and appreciation. Speaking of appreciation, remember to say thank you — often! Few people get too much appreciation at work. Email the SME's supervisor to share positive comments about the SME. Finally, celebrate. Celebrate at the end of the project with your SME.
The bottom line is that you want to find the best SME available to you. Once you find your SME, do everything you can to build and maintain a positive and productive working relationship.