One of the features that increases your productivity are the minor modes that can be enabled to help your work. Abbreviation mode, Foot note mode, flyspell mode are some of the minor modes that allow you to correct typos, add footnotes and do spell check.
In addition there are lots of other minor modes have been added to the main branch of Emacs that can complement the existing ones.
Like Table, that allows you to create ASCII tables to align text and also create spiffy text based tables. It also provides a LaTeX export function that helps in creating a LaTeX table. Frankly, I've been using the table-insert function to create all my LaTeX tables. Saves me the repetitive edit-view-correct cycle by a huge margin.
Another simple one is ruler-mode that puts a ruler on top of the text area. If you do a M-x find-file RET ruler-mode, the commentary will explain what are the features you can use enabling the minor mode. Tremendously useful when working with fixed width data; slightly better than following the mode line for the column position, I dare say.
And one other under appreciated mode for newbies and intermediate Emacs users is outline-mode. Found in org-mode and one that can be set in LaTeX mode (with AucTeX), the showing and hiding of the sections allows one to navigate large documents quite easily. Instead of scrolling up and down the document, it's easier to fold the arbitrary sections to focus on the section at hand.
