Believe it or not, there is a philosophy and a method behind which fonts should be used depending on the situation.
Fonts are divided into two basic categories, Serif and Sanserif.
Serifs are the little tails that extend from the ends and various parts of some fonts. The most commonly used serif font is Times.
Sanserif fonts do not have these tails, this would include fonts like Arial and Helvetica.
When should I use a font with serifs?
The purpose of these serifs is to create subliminal lines for the eye to follow and keep its place. Serif fonts are meant to be read in large blocks of text at smaller sizes, which is why they are a popular choice of newspapers and magazines.
When should I use sanserif fonts?
Sanserif fonts are intended for headlines, and small pieces of text, not large blocks of text. If you are creating a larger publication such as a newsletter, it is highly reccomended that you do not use a sanserif font for the body text. On the flip side, most of the time it is better to not use serif fonts for headers or logos. Text in logos and headers is meant to grad your attention and pull you into to read the body text. Serif fonts, thought easier to read up close, lose their definition at greater distances and are not as attention grabbing.
There are exceptions, there do exist very bold serif fonts designed to work well at greater distances. These are referred to as slab-serif fonts.
Some general font usage tips:
Never stretch a font! A skilled typesetter will never stretch a font, it destroys everything that the font was designed to accomplish visually and it is a dead giveaway that the layout was not professionally done. If you need to make text fit in a space, try changing the letter or word spacing, using a hyphen, or changing the font size. Never resort to stretching text!
Always select a bold font for your logo. If the logo is not readable at great distances, it is a failure. Look at all major national company's logos, pretty much all of them have a bold font, there is a reason for that.
As always, please feel free to ask any questions about specific situations, I love to answer them. Thank you!