That's a great idea from Lynn to shadow a therapist.
About 3 years ago, I also returned to beauty after a long break to raise a family.
I set up a home salon and understand you can lack confidence in your self and you feel you need a refresher course. However, I also went on a course at the Carlton Institute for facials and had one booked for massage but actually cancelled it as, I really felt I did not gain much from the facial one. The course is so short it has a lot to get through and most of what they cover is basic and it will still be installed in you from your previous training and work experience.
I actually found the most useful way to spend my time and money was having treatments at various salons, practising on friends and family and buying up to date educational books to re-learn from, trades magazines, beauty show visits etc. Also,having treatments at local beauty colleges is great as you pick things up from the tutors instructing their students.
Also, if you plan to work for yourself and choose good, professional brands, you can go on their in house training courses where you will learn far more in depth information than you can on expensive short refresher courses.
Hth. Good luck!