This review is from: What Can I Do to Help My Child with Math When I Don't Know Any Myself? (Paperback)
A lot of this book is about more general study skills than specific Math skills, but I found lots of useful tips in it.
For instance I enjoyed the section about the difference between passive and active memory.
There is also a crib sheet for adults about all the Math concepts your child will cover if you need to brush up yourself.