I appreciate any perspective from people who are much older. I see having a family someday as one of the larger financial variables for me in the coming decades, so I try to prepare for that as best I can.
In defense of my age (and implied lack of life experience), I've unfortunately had significant medical issues in my twenties, which in turn led to some decent sized bills I've had to take care of, so I know a bit about troublesome times.
Be prepared for the family thing to cost a whole lot more than you think. I was living on about 10K/year back in the day. I assumed at worst my future (at the time) family of 4 would live on 40K/year, with "economy of scale" reducing it to the mid 30's. Ha! Sure I was fine living in cramped quarters, spaghetti every night, one new $5 shirt / year. Doesn't really work that way with kids. Essentially expect after about three years to wonder where all your previous three years' income has gone. (I'm only 3 years in, so I'm not sure what comes next--I assume it's "make a budget", which I did diligently in my 20's, but it's much more difficult to find time to make a (now, negotiated!) budget with munchkins fighting for attention 24/7).
As a corollary, be prepared to worry about money way more than you had anticipated back when you were 30 and diligently following Mr. Moustache to an early retirement.
As far as career advice, it's tough to say. I've had a good career but feel I'm in a difficult spot now. The last five years I've been independent but 95% of my work has been as the lone dev for one startup, whose best days suddenly seem to be in the rear-view. It's been great work and the job has been wonderfly flexible, but now I'm left to wonder, if they die who wants to hire a 40 year old developer (a really good one IMO but who's to say) with just kind of a miscellany of experience and hasn't worked with a team in five years (especially in small-town Michigan). Who knows, maybe lots of people. But I think the moral of the story is "don't paint yourself into a corner". Do good work, work with lots of people (my mistake), make them respect you, and you should be alright in the end.
In defense of my age (and implied lack of life experience), I've unfortunately had significant medical issues in my twenties, which in turn led to some decent sized bills I've had to take care of, so I know a bit about troublesome times.