@andrewgthomas I graduated with a BFA in illustration about 6 months ago. While I was in school I took on a hand full of freelance jobs and honestly I think it was crucial. Not only did it build my confidence so that when I graduated and took on other gigs I didn't have that fear of "oh god, I've never really done this before", but additionally I had some really great supportive instructors who I was able to approach for their insight on various things. I showed thumbnails to one teacher before presenting them to the client to get his take on how I could present my best work in the early stages, and on a different project when I had some communication difficulties with a client, I had a teacher who was happy to listen and offer advice. If you're in a program where you're able to forge real connections with your instructors and be their genuine friend, they're often happy to lend an eye to look over things or make sure you're not going to screw yourself over with certain contract terms.
The thing I imagine this fellow is saying is to not get ahead of yourself and think you're all that and a bag of potato chips just because someone is paying you. If you're able to remain humble, acknowledge that you're still learning, and it won't take time away from your studies then I would say go for it.
The biggest thing I've learned since graduating is that I didn't feel like I was ready, and probably never will. We continue to learn and develop both our artistic and interpersonal skills the more we practice them, so I'm a big supporter of 'fake it til you make it' as long as you're putting your best effort into everything you do.
