Seven weeks into an AI Engineering internship (alongside the IBM Data Science Professional Certificate), I've picked up a few things I genuinely wish someone had told me on day one. None of these are deep technical lessons — they're more about mindset and habits, the kind of stuff that doesn't show up in a syllabus.
If you're about to start something similar, here's what I'd tell past-me. I learned this the hard way while fine-tuning a sentiment analysis model — accuracy kept climbing each epoch, but validation loss was quietly getting worse the whole time. It was overfitting, and I almost missed it because I was only watching one number. Now I check training loss and validation loss together, every time.
I expected Random Forest to beat Linear Regression on a house price prediction task. It didn't — Linear Regression won by a solid margin. With a small dataset, the simpler model generalized better. I've stopped assuming complexity equals performance.
Building a Cat vs Dog classifier by only training the final layer of a pretrained ResNet18 — instead of a whole network from scratch — felt like skipping steps I was supposed to do the hard way. It's not cheating, it's just how the field actually works. I wish I'd trusted that sooner instead of assuming "real" learning meant building everything from zero.
Somewhere around week 4 or 5 I realized most of my time wasn't spent tuning models — it was spent understanding, cleaning, and preparing data. That's not the part that gets talked about, but it's the part that actually determines whether anything downstream works.
I started documenting these weeks partly for accountability. What I didn't expect was that explaining a concept well enough to write about it forces a level of understanding that just doing the exercise doesn't. If you're on the fence about writing publicly, it's worth it even if nobody reads it.
None of this is groundbreaking advice, and honestly most of it I only understood after getting it wrong first. If you're just starting an AI internship, a certificate, or learning ML on your own — you'll probably relearn a few of these yourself, and that's fine. It sticks better that way.
If you've got your own "wish I knew" moment from learning AI/ML, drop it in the comments — genuinely curious what other people's version of this list looks like.