Font choice guidelines, and my preferences

Sans-serif fonts are more readable on screen.
Serif fonts are more readable in print.

Some fonts, were designed to be used on-screen, eg Arial, Verdana, Georgia. They typefaces don't look so good in large sizes or in print because of their design. On the other hand, many classic fonts that were designed for print don't look good on-screen eg Times New Roman.

Some font characterisations:

Humanist fonts have subtle curves and look "friendly." The letter structure letters is are based on hand-drawn letterforms - eg if you draw an "O" with a pen, it isn't completely round. Good for healthcare, charities or cases when you want to look "human".

Some examples: Gill Sans, Palatino.


Geometric typefaces have letter structures based upon geometry. They may have a completely round "O," or strong contrasts of thick and thin. They end to being very modern and fashionable. They'd be good for content that is maths or engineering, or fashion related.

examples:
Bodoni - which was built by geometrically rationalizing serif letterforms
Futura and Rockwell, which are both geometric typefaces.


Realist typefaces are in the middle. They have more abrupt curves, and a sense of rationality and stability.

Examples:
Helvetica, which has a a sense of being visually inert – almost "invisible."
Arial (which is based upon Helvetica)
Georgia



A good way to identify fonts is to look at the lowercase "n":
Gill Sans (Humanist) has a gentle curve.
Futura (Geometric) has a nearly symmetrical curve, .
Helvetica (Realist) has a more abrupt curve. It's as if the shoulder is a piece of metal that has been bent to the designer's will.


Pairing fonts
Rule of thumb: Choose no more than two - one serif, and one sans-serif

Either either be very similar, or very different from one another.