While the advice in these sources is directed to summer associates, it it pretty much applicable to all types of summer programs.
Stay up to date by creating alerts to catch news about Summer programs. Some suggested sources include:
American Lawyer Media (ALM) content on Lexis Advance and Bloomberg Law. This collection includes National Law Journal, American Lawyer and some of the best regional legal news publications. Run your search and look for the link shaped like a bell found top-center to set a schedule for updates. 
Bloomberg Law (BLaw) also has a number of good legal newsletters that report on the major issues of the day. Setting up alerts is a great way to keep an eye on the matters that may be of interest for the organizations where you will be working. BLaw newsletters report on the legal industry, too.
Set up Google Alerts to monitor Summer program news or events that are important to you. These alerts reach a number of business and specialized webstites, like ATL. Google Alerts work very well but some fine tuning may be necessary.
Check Lexis, Westlaw and Bloomberg's Summer Success pages for other guidance, tips, and useful info for thriving this Summer.
Lexis' Prepare to Practice. Here is a link or find access points on the Lexis Law School Portal. Materials here are geared for all types of law organizations: courts, government, firms (big and small), and public interest. Includes materials for sharpening your research skills and the Lexis Summer Survival Guide. Site also has wide ranging advice, from etiquette to offer acceptance.
Bloomberg Law's Tools for Summer Success includes additional insights on conducting research, working efficiently, communicating effectively, and more. This guide includes research tips for the Bloomberg Law platform and Bloomberg Law's Practical Guidance content.
