With centers across the country, this is a great place to get hands-on tutoring at every grade level.
This PDF gives a number of strategies to help students who struggle with various difficulties in math. Some of the strategies are mnemonic devices that can be used with visual schedules; others are approaches to teaching.
Through the University of Missouri, this page gives a list of math interventions with brief descriptions and links to dive deeper into an intervention you feel may help your struggling student/child.
This PDF from Hanover Research goes in depth on the best math interventions. This document is five years old, but still relevant. It looks a bit dense; however, the table of contents can direct you to specific interventions for you to explore.