Collin,
Tutoring Adult ESL Learners is no differentr than teaching a class of Adult ESL Students:

Here are some tips and strategies:
Remember to use lots of visuals with the students- pictures, pictures and more pictures for the different vocabulary words
Include activities involving listening, speaking, reading and writing in order to present a balanced learning experience.
Use the three different learning modalities- Auditory, Visual and Kinesthetic- within your teaching/tutoring
Go slow and remember to speak clearly and slowly with your students
Use more why and how questions with students in order to insure that students understand/comprehend the information you are presenting to them.
Dr. Yanni Zack