I'm definitely a fan of structured education. After all, what I learned about DP I learned from a fantastic college course. Glad to hear there are online resources for people to get that kind of education, so thanks for sharing!
Hopefully, an article like mine can help those who are not able invest in more lengthy study, or just need an additional perspective.
The tricky part to learn, and one that I'm sure comes with experience, is how to identify the subproblem + recurrence relation. One thing this clarified for me is the construction of the grid and how it is dependent on inputs because of the DAG. But you can have a recurrence relation that uses more than two sub-problems. i.e. the DP method for calculating Levenshtein distance involves a recurrence relation with 3 previous values (subtraction, addition, substitution).
You're absolutely right about figuring out the subproblems and the recurrence relation. I've found that knowing how you're going to use the recurrence relation is a first step to coming up with the right relation. For example, knowing you'll cache the results in a table means you're on the lookout for a function that has integer inputs, because you want the values to be indexed and ordered.
After that, as you said, practice is key. I'm working on a follow-up article that'll show some tougher examples, which should help provide more exposure. Forget three sub problems; one problem, the chain matrix multiplication problem, uses O(n) subproblems!