I believe anyone working in online learning should be a serial student of online courses to master their craft. Obsessively taking classes gives a learning designer two powers; the first it allows them to understand how excellent and poor courses are put together, the second is they get empathy for the students that will take the courses they build.
Use only that which works, and take it from any place you can find it.Bruce Lee
Knowing the learning theory, research, and technology is essential. Applying design principles will maximise the return of these three skillsets. Still, nothing will give you the sensitivity like being an online student.
There are lots of great online courses that you can find for free that are doing some exciting things such as KhanAcademy.org, Brililiant.org, the Youtube creators academy, and the free sample modules of Quantic.edu. Udemy has some great courses that can be reasonably cheap if you catch them in the sale, and the Interaction design foundation courses are essentials for any aspiring learning designer.
Nothing is quite like a cohort-based course though, so budget to do at least one per year or get your work to pay for it. Learning in a cohort can be much more attractive as an experience than self-paced courses and more rewarding, and building an online community is an art form that takes time to learn. An MIT course on the Get Smarter platform was the last one I took. The short course can be bundled together with other MIT online courses to get a Postgraduate certificate from the world-class University.
Get in touch on Twitter to let me know any good courses you have taken and what they have taught you about learning design.