1. To be legible: Your business name needs to be able to be read easily, quickly and clearly. Make sure the letters are spaced well, so that they don't bleed together. Make sure that the letter shapes are distinguishable from one another – that your lower case i doesn't look like an l, for example. Also ensure that you can read it at a glance; most people won't pore over your logo, they'll just skim it.
2. To be scalable: Your logo should be able to be blown up to the size of a billboard and scale down to the size of a postage stamp, and to be readable across all of these different options. Make sure that the legibility doesn't suffer when the size is changed.
3. To make your business name look good: Choose a font that includes good letter shapes for all of the letters in your business name. For example, some lower case g's look pretty funky – so if your business name includes a g, you may want to stay away from fonts that include strange g's.
Also, if you have a long business name, consider using a lighter font so that your business name doesn't dominate the entire logo – you want the font to be balanced with the icon. This sample shows what happens to a logo when the fonts are in balance versus out of balance:
You might also want to vary the font so that the most important words in the name stand out, and to give the logo more visual interest. This can be as simple as changing color, size or weight/boldness of the font, or using 2 fonts together for more variety. Here are some examples of those techniques:
4. To support your brand definition: This is the last job that your font has, and this can show itself in a few different ways in your logo, depending on how much of your brand story is told by your logo icon.
If you've told most of your story through the icon, then the font just has to support that.
This logo is clean and modern looking logo icon because their business's personality is cutting-edge. When paired with a modern, bold font, the logo's meaning is reinforced. But, if they used a traditional serif font for their text, the font would contradict the icon.
In this logo, the icon and font both say "strength" and "well built". But, if we switch the font out to a lighter version with a bit of a tilt to it, the logo suddenly looks much less stable and like it's ready to topple over.
But, if there's still a bit of your story to be told, then a contrasting logo font can help reveal the rest of your brand. This creative consultant wanted to show that she could be both highly creative and artistic as well as business savvy. The font brought an otherwise eclectic logo back down to earth. If she'd chosen an artsy font as well, then her seriousness about her business would not have been communicated as clearly.