Marcin Borkowski (mbork) has a short list of Emacs configuration tips that you may find useful. All of these are documented, of course, but it can be notoriously hard to dig out information of this type.
For example, one tip that I find immediately useful is the configuration to inhibit AUCTeX from asking if I want to save my current TeX file before executing whatever command 【Ctrl+c Ctrl+c】 will execute. Of course I want to save the file; the command will likely not do what I want otherwise. A simple configuration change will just save it automatically without bothering you.
Most of you will know some or all of these tips already but it’s worth scanning the list to see if there’s something new you can use.