There are tons of ways to get starting doing DH development, and I’d say the only ways that are right are the ones that are right for you and the things you’re interested in. I’ve been ridiculously lucky in the opportunites I’ve had to learn and grow, and looking back at that I can’t imagine how difficult it would be to take that same path today.
The one thing I would say is, regardless of where you start or how, don’t apologize for it. Don’t apologize for being new, or for not knowing answers, or for asking what you may think are silly questions. They’re usually not silly questions, and even if they are silly questions, or if the answers are readily available through that ultimate smartass service “Let me Google that for you,” don’t apologize. Remember, certainly, that you can go find the answers yourself. But I’ve found there’s something encouraging by having another person help you find the answers.
This is almost universally the first piece of advice I give to incoming graduate fellows at Scholars' Lab, and any other graduate students I help through consultations. (I’ve also had tell this to a few faculty and staff members as well.)
And if you are someone who is helping someone, don’t get annoyed, don’t be patronizing, and don’t make people feel like they have to apologize to you for asking you a question. This does no one any good.
This XKCD comic pretty well sums up how we all should approach this: