Courtesy of JTR from The Art Of Not Asking Why, here’s a handy tip for dealing with window placement when bringing up a Dired buffer. There are two problems.
The first doesn’t really concern window placement. Most often JTR wants to bring up a Dired buffer for whatever directory he’s already in. The easy way to do that is to use dired-jump (bound to Ctrl+x Ctrl+j) to open a buffer in the same directory as the current file.
The problem with that is that it opens the Dired buffer in the current window. JTR doesn’t want that. He wants to open Dired in some other window so that he can see his current file and the Dired buffer. The answer to that is simple: just ask Emacs to open Dired in another window. There’s a general protocol for doing that. Simply use Ctrl+x 4 Ctrl+J to call Dired. That will open Dired in the same directory as the current file but in another window.
The Ctrl+x 4 … works for a lot of commands. I use it to open files or buffers in another window several times a day. I used to consider it an esoteric maneuver but now I use it all the time. You can also open your windows in another frame by using 5 instead of 4.
The 4/5 protocol doesn’t work for all commands but it does for a lot of them. It’s a real time saver that I use repeatedly. It’s well worth internalizing.