The post has many good suggestions! To them, I would add:
The mark ring. Whenever you place a mark (highlighting a region), its place is also added to a ring, and you can jump between them by pressing "C-u space" (or "C-x space" for pop-global-mark, which will jump between buffers). Many commands that move a long way add an implicit mark, so this works quite well as a "where was I..." command.
For "dynamic abbreviations", I recommend pabbrev (http://homepages.cs.ncl.ac.uk/phillip.lord/download/emacs/pa...) - when Emacs is otherwise idle, it starts building a lookup trie of prefixes to frequently used words, so it will suggest completions under the cursor as you type. I love it.
I much prefer iswitchb to the default buffer switching system. YMMV.
Don't forget about learning Emacs lisp, either! It adds quite a bit of flexibility to Emacs. It's kind of a crappy, backward Lisp dialect, but still tremendously useful.
Finally, learn to use the help system. Emacs's naming is really idiosyncratic, but it gives you several powerful ways to look things up, so you don't have to memorize everything.
The mark ring. Whenever you place a mark (highlighting a region), its place is also added to a ring, and you can jump between them by pressing "C-u space" (or "C-x space" for pop-global-mark, which will jump between buffers). Many commands that move a long way add an implicit mark, so this works quite well as a "where was I..." command.
For "dynamic abbreviations", I recommend pabbrev (http://homepages.cs.ncl.ac.uk/phillip.lord/download/emacs/pa...) - when Emacs is otherwise idle, it starts building a lookup trie of prefixes to frequently used words, so it will suggest completions under the cursor as you type. I love it.
I much prefer iswitchb to the default buffer switching system. YMMV.
Don't forget about learning Emacs lisp, either! It adds quite a bit of flexibility to Emacs. It's kind of a crappy, backward Lisp dialect, but still tremendously useful.
Finally, learn to use the help system. Emacs's naming is really idiosyncratic, but it gives you several powerful ways to look things up, so you don't have to memorize everything.