Pierre Lecocq has a nice set of Emacs tips for developers. I've been meaning to write about it for a while now and Lecocq has recently updated it to include tips for Ruby, Python, C/C++/Objective C, Go, PHP, Java, and R developers so this seems like a good time.
If you follow the link, you land on his Github page where the README is the Table of Contents for the tips. Rather than going through them, I'll just send you over to take a look. Some of the examples have animated gifs so it's worth checking the tips out.
I see a lot of posts on Reddit asking how to set up Emacs for language X. Provided that X is one of the above languages, these tips may help. The sections on tips for developers is mostly links to other resources but it's convenient to have the links in one place.
The other sections are more general tips that all Emacs users will find helpful. Again, these tips are mainly for beginners but you may find something useful. Use the TOC to explore things you think might be interesting.