Michael Lopp, known as Rands, writes about engineering management, leadership, and working with nerds, and runs a leadership Slack community.
Commenters repeatedly recommend the blog and his book Managing Humans as timeless, funny, and useful for new managers.
Hi there, I'm quite new to engineering management as well, with approximately one year of experience. I've had some great mentors, as well as a reading list passed down to me. I'll highlight those I found as having the most impact for me.
At the top of the list is "Managing Humans: Biting and Humorous Tales of a Software Engineering Manager" by Michael Lopp[1], which was recommended to me by a manager who helped me get my start in engineering management. This book touches on a lot of the nuances in dealing with people and, as an introvert, I found this really helpful. The same author blogs under "Rands in Repose[2]" which has much of the content from the aforementioned book available for free.
While in the people category you'll also get a lot of recommendations for "Drive!" by Daniel Pink[2], which is a book about intrinsic motivators (autonomy, mastery, purpose) and how they are more important and effective than extrinsic motivators (e.g. money), particularly for knowledge workers. My personal advice, however, is to watch his TED talk[3] which is a great summary of basically the entire book. In this same category I could also recommend "The Great Jackass Fallacy" by Harry Levinson[5].
Now on the wall between people management and engineering/project management is "Slack" by Tom DeMarco[6], which is about how organizations and managers tend to run their staff at 100% capacity. As the book points out, however, this is a good way to not only burn people out, but it also…
Shortly before I started managing engineers I read "Managing Humans" (I'd already been following http://www.randsinrepose.com/) and found it helpful. One of the best resources I found was (luckily) my own boss. Find others in a similar (or higher) position and talk with them regularly, openly, and candidly about any challenges you're facing.
I wish I had better advice, but what you'll find is that being a good manager/team lead is at least as hard as your old job (and probably harder). Continuing to do your old job alongside it, while probably a good idea for your own job satisfaction/sanity, will only make it harder.
Random bits of advice I find helpful:
* Your primary job is to shield your direct reports from management BS (false priorities, unrealistic deadlines, company drama); while this is less of a problem at a small startup, don't ignore it. Your secondary job is to make your direct reports look good; promote what they're doing and make sure what they're doing is aligned with the company's goals.
* Schedule 1:1 meetings. See Rands' advice on how to structure and run them, but basically keep them short, informal, and regular. Start with a softball and use it as a time for your direct reports to warn you about any upcoming problems that may be bubbling. Avoid the temptation for status reports, one larger team meeting instead, etc. Sit down with each individual direct report and get to know them better.
* Set clear goals and priorities for everyone.
*…
The fact of the matter is that a lot of technical people who are geniuses technically do not have the qualities necessary to be good managers. Good managing requires ability to communicate up, down, and across the corporate hierarchy and the political minefield that comes with it.
Good managers will balance out good technical people in terms of skillset, and help their team to do their job, while also coaching them in the areas where they are weak (and if the manager is weak technically, then obviously technical coaching is not in scope). Good managers will filter what reaches inside their team from the outside and protect their team from crap while captaining the ship forward. They know their weaknesses and also know that good leadership requires hiring people who are smarter than you are, and then helping to facilitate the magic that can happen when good people get together.
Having managers who are strong both technically and in a business sense is rare. There are only so many Elon Musks in the world. But when you work with one, your work becomes very enjoyable.
At the end of the day, team members don't have visibility as to what managers do every day. This blog is great for understanding this stuff: http://randsinrepose.com
http://www.randsinrepose.com/cat_management.html
Here's another idea: Since your friend is coming out in 9 months anyway and there's so much risk involved in trying to sneak in a programming book, he should probably spend his time developing another equally useful skill: writing well.
As many other successful programmers have noted (Spolsky, Yegge) and demonstrated, effective communication, especially through writing, is a very useful and necessary skill for a programmer. So, maybe you should send him just some good books on writing well.
In general books, I can think of Strunk and White, On Writing (by Stephen King). But some examples of good writing about programming could also help:
The Best Software Writing (edited by Spolsky)
Joel on Software (the best articles from his blog)
Steve Yegge's blog posts (others might disagree but I think he is an excellent writer).
Paul Graham's essays
raganwald's old blog - http://weblog.raganwald.com/
James Hague's blog - http://prog21.dadgum.com/
Rands in Repose - http://randsinrepose.com/
To add a few that span outside entrepreneurship, but are of course very valuable to entrepreneurs:
Inspired: How To Create Products Customers Love (http://www.amazon.com/Inspired-Create-Products-Customers-Love/dp/0981690408?ref=as_li_tf_tl?ie=UTF8&tag=mypred-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0932633439) - The best if not only required reading for product management
Peopleware (http://www.amazon.com/Peopleware-Productive-Projects-Teams-Second/dp/0932633439?ref=as_li_tf_tl?ie=UTF8&tag=mypred-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0932633439) - Great read on managing and understanding people as it relates to organizations
Managing Humans (http://www.amazon.com/Managing-Humans-Humorous-Software-Engineering/dp/159059844X?ref=as_li_tf_tl?ie=UTF8&tag=mypred-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=0932633439) - Obviously on management, you can read much on this http://randsinrepose.com/, though the book does a great job of consolidating it
I hope financial growth is not the only thing that drives your career, because if it is you won't really get nourishment out if it. And a happy career is a good career.
That said, if you are really considering a management role -- not because it pays better, but mainly because the job excites you and you love the challenge to keep both your engineers and your boss happy -- Michael Lopp's blog [0] and book "Managing Humans" [1] are certainly some things which you want to read.
I personally also love Meri Williams' blog, which also contains all her talks on managing geeks. In my personal opinion both are the kind of people you would like to have to run your team(s), and their insights on how to properly manage people are invaluable.
[0] http://randsinrepose.com/
[1] http://www.managinghumans.com/
[2] http://blog.geekmanager.co.uk/