It's not as hard as you might think.

After I had completed my core courses (just 200, 202, and 204 at the time) I knew that I wanted and needed to get some practical experience, so I sent emails to several libraries that I was interested in working in. I let them know who I was, what courses I was taking, my professional interests, and why I was interested in working at their library. (Do some research to select libraries that may be a good match for you. You'll also find the contact names and email addresses that you will need on the library website.)

A few let me know that they were not interested in or able to support an internship at that time.

A couple didn't reply at all.

One, however, was very interested. We scheduled an interview and we arranged an internship for the next semester. I acquired some great practical experience, met others in the field, got to know the inner workings of the library, and created an internship log that I used to help satisfy several of the core competencies for my ePortfolio.

So "cold calling," as it's sometimes known, can work, but be aware that a lack of a formal internship structure can be a mixed blessing. If no one knows what to do with you, you may end up doing repetitive paraprofessional level tasks. If you plan to approach a library or organization that does not have an internship in place, have an idea--or better, several--of possible projects that you would like to undertake. Don't leave the burden of keeping you occupied and filling your required hours solely to their discretion. You'll be happier and have a more worthwhile experience if you have some goals sketched out in advance.