Anthony - This is a tough one because I think that different strategies work for different students. At our middle school we ran a Saturday School program and there were many students who thrived because the numbers were smaller and they were able to get time and support while working on basic skills.
While these are not detailed effective strategies I thought the following might give you some ideas to ponder and places to start:
Good luck to you - and I hope that others share their ideas and best practices to help you find what you are looking for.
- Critical Issue: Beyond Social Promotion and Retention—Five Strategies to Help Students Succeed
- 4Faculty.org - although not currently funded- this site has some great ideas