When choosing and combining typefaces decisions are made according to the demands the text and media makes on the typeface. For instance, text type or headline? business card or billboard? printing: letterpress, digital, offset or online, app, or film?
Typographers read their content for concept as well as for typesetting details; Do we needacronyms (like our first exercise) requires a typeface with “true” small caps or an annual report with financials requires tabular figures. (smallcaps? are numerals important? non-lining numerals? tabular numbers, or three-quater-height lining numerals?) or do I need a matching sans-serif? a large family?
The fastest, easiest, and most visible improvement you can make to your typography is to ignore the fonts that came free with your computer (known as system fonts) and buy a professional font (like MyFonts equity and concourse, or others found in font recommendations). A professional font gives you the benefit of a professional designer’s skills without having to hire one. (Butterick’s Practical Typography)
If that’s impossible, you can still make good typography with system fonts. But choose wisely. And never choose Times New Roman or Arial, as those fonts are favored only by the apathetic and sloppy. Not by typographers. Not by you. (Butterick’s Practical Typography)
Choose the typeface for the job. This slide from Jason Santa Maria’s 2011 Build Talk:
Bodoni is a display typeface:
Meta is better for body copy:
In addition all advanced typography students should read Jessica Hische’s writing on typography: Upping Your Type Game. Especially: Choosing The Right Type where she explains how to choose a text face. The following set of black slides are a taste of Jessica shares like choose a text typeface with a variety of weights:
Choose a text typeface with a true italic (JH):
Choose a text typeface that is spaced well.
Above: “Avenir’s more open spacing make it a better text face than Helvetica.” (JH)
Below, “choose a text typeface with eveness of wieght.” (JH)
Above: “Notice how the stem on the n is less wide at the top to compensate for the weight at the join.”
If you choose a sans serif for a text type — choose a sans that passes the “Il1” test. (JH)
“Thinking Conceptually: Defining the Mood” (JH)
“Pairing Typefaces: Choose a super family” (JH):
Above: Freight Display, Freight Text, and Freight Sans by Darden Studio.
“Choose a typeface with similar characteristics.” (JH) Learn from Jessica about “skeleton, meat, and clothes” of a typeface.
Part Two: On Combining Typefaces
Another great Bringhurst “tip” regarding combining typefaces: “Just don’t do it.”
Choose a typeface with a large family and stick with it — many a text can be set beautifully in only one typeface! The safest, (smartest?) bet in creating continuity in visual form is to rely on a single large type family. Choose a typeface with various weights and proportions within the family provide a range of versatility.
According to Bringhurst its best to pair serifed and unserifed faces based on their inner structure. (6.5.5) For instance if you choose Futura, a geometric typeface consider perhaps Bodoni whose forms are based on geometry also.
When setting a typeface side-by-side consider their x-height and extension.
From the online article “Four Rules For Combining Typefaces” by Allan Haley. 
from: http://assets.dynamicgraphics.com/dgmfigures/14846.gif
When combining typefaces limit combinations of typefaces. Keep it simple.
Hoefler & Frere-Jones, Four Ways to Mix & Combine Typefaces
