I’m so used to working openly by default that I sometimes forget that for many (most?) people it’s a new, and sometimes quite scary, step.
Alfonso Sánchez Uzábal pointed to choosealicense.com from GitHub, which makes it simple to choose an open license for your software project. Moodle, for example, is GPL but it gives other examples such as MIT and Apache.
For everything other than software, you’re probably best off with Creative Commons licenses. I’ve been using these for the last fifteen years now on my work and highly recommend them.