Establish expectations. Clarify in writing what level of autonomy and responsibility you expect for your TA. Set standards for performance meetings, reviews and evaluations.
Discuss the course material. Decide what course material (such as syllabi and exams) you will develop and what material the TA can select. Provide some opportunity for the TA to create her own course content, such as writing an exam or a unit within your syllabus.
Provide copies of any written expectations or course material that you developed to the TA. Review the documents with her and answer any questions or issues that may arise. Include contact information to help the TA contact you quickly in case any problems occur during the term.