NFSA online or classroom courses.
Lots of helpful guides/ data sheets of frequently used fire protection products.
Paid-for classes are invaluable, but if you're an intern I don't know many companies that will send you to them given your temporary status. Read the material data sheets direct from the manufacturers' websites. Not just the sprinkler ones either-look at fittings, hangers, everything. If you can get an idea of the requirements and testing parameters of some of this stuff, the NFPA Standards might make some more sense rather than just mulling through them right off the bat. MeyerFire is the website I went to every day for the first few months just to soak in what I could and play with the tools. It's still an awesome resource for me. Your coworkers are also sources of knowledge. Hopefully you work with people who are passionate about the industry and simply asking them something you're not sure about will get them to talk so much they won't "shut up" about it. One of our senior designers taught me in the first day of my employment the same amount that a TYCO class taught in two days of classroom.
I graduated about 5 years ago, but I resonate deeply with you and your desire to get up to speed and dive into things. What I found, was that unless you are in a fire protection specific firm or field, its going to be up to you to try and chart your path and develop professionally. Depending on your background and education, I would say that the best advice I can think of is to diversify your experiences and look into all aspects of fire and life safety. When you start to understand all of it and how it fits together I think you start to see the code a little more clearly and how the code provides options. NFPA has been pushing the life safety ecosystem very hard, and it truly is. The biggest lesson that I have come to understand is the communication of the technical and code language that we work with every day. It may make sense to you and to those in your office, but your stakeholders may have limited to no experience with the content of your discussion. Just some initial thoughts, but your motivation to dive in is great. And the fact that you are already reading this blog is absolutely great as well. This site has substantially helped me to understand the field more over the last couple years that i have discovered MeyerFire.
The best most valuable experience I had was working in the field as a sprinkler contractor installer for a year. I started right out of college as a foreman's helper and learned a huge amount of knowledge from that guy. I then designed for two years for the same sprinkler contractor and continued to learn the basics. Now I'm on the engineering side and now I realize that textbook knowledge is one thing, physically learning is another.
Explosion Protection & Prevention
Fire Detection And Alarm Systems
Flammable & Combustible LIquids
Information Sources For Analysis
Means Of Egress
Passive Building Systems
PE Prep Guide
PE Prep Series
PE Sample Problems
Smoke Management Systems
Special Hazard Systems
Types Of Analysis
UFC 3 600 01
Water Based Fire Suppression