The federal Institute For Educational Sciences has a very useful and careful synthesis of how to help students enter and be successful in college. It is authored by five leading scholars who use explicit criteria for weighing the scientific evidence for various programs and practices. It is the most comprehensive research synthesis I have seen. The results are organized around 5 key themes such as : surround students with adults and peers who build and support college aspirations. Programs like Upward Bound and Talent search are evaluated based on the quality of research for each intervention.
You can down load it at http://ies.ed.gov/ncee