Couchsurfing is a noncommercial internet community that connects travellers and locals worldwide. Through the Couchsurfing community you can find locals at your destination that can provide advise, other tourists that can accompany you on your trip, and even a couch to sleep on for a few nights as a guest.
There's a Couchsurfing community that operates in Costa Rica, they have both a group on the CS site, and a group on Facebook.
Couchsurfing might sound strange or risky, but it's mostly safe as long as you're familiar with their ratings and reference systerm. Take a look at the site, and ask around on the CS group, you'll find many people willing to help you plan your trip in Costa Rica.