What sources should you use?

I'd say 'it depends'. It depends on your learners' ages, proficiency levels, motivation levels, interests, end goals, and many other considerations.

Will you be tutoring individuals or groups?

I'd interview each student and maybe even give him or her a short diagnostic test to determine his or her proficiency before doing anything else. Custom-made syllabi for each learner are probably best. If you need info on designing a diagnostic test, there is a fabulous book out there on TEFL testing by a guy named David Harris. It's an old book and may be hard to find, however.

Good luck.

SS