If you're a middle or high school math teacher, you may want to check out the practice guide that the Mathematica Policy Research prepared for What Works Clearinghouse (WWC). Titled "Teaching Strategies for Improving Algebra Knowledge for Middle and High School Students," the guide describes three recommended strategies. Each strategy is written up in a separate document and contains implementation guidelines.
"Use solved problems to engage students in analyzing algebraic reasoning and strategies." (Minimal evidence)
"Teach students to utilize the structure of algebraic representations." (Minimal evidence)
"Teach students to intentionally choose from alternative algebraic strategies when solving problems." (Moderate evidence)