Johannes Neumeier

Hrant H. Papazian said:

Use only an excerpt and it's Fair Use.

Fair Use and using something for commercial gain are not quite the same, though, are they. It's not just the length of what you quote, but the motivation, that matters most for fair use - like research, education, commentary, news, etc.

Or by way of example, it wouldn't be Fair Use for L'Oreal to advertise with quote's from George Martin's Song of Fire and Ice, describing the Lannister's fair hair, even if they only use just one phrase.

One aspect of this discussion, especially in digital screen context, that I find interesting and largely unexplored is the notion that stylistic aspects of the sans are of importance in its supposed better legibility, or at very least in its perceived dominance in this domain. When compared to serifs typefaces, sans can be ascribed a more utilitarian, clear and rational tone (in most types, anyway; certainly grotesques, most geometrics, and surely a good amount of humanists as well).
It could be argued that computers, and screens as their typographic user interfaces, needed to have a typographic voice that echoes the functional approach of the machine itself, and how we humans expect it to look like. Or to put it a tad poignantly, a device that can in a split second make more calculations than a human in a lifetime simply has no room for the grace and refinement of an antiqua.

To me personally this trend mostly speaks of a longing for the analog. Be it illuminated scripts with color decorations, carvings with inlayed color, or woodblock prints with layered impressions of different color, the current trend in these types (be in implicit sets to be used in conjunction or multi-color font formats) relives that tangible aspect of typography - which readers young and old alike have come to reminisce about. As such, I think it's worth cherishing these new forms as stylistic evolution.

From the point of view of designing type, however, I feel it's a gimmick. In the stylistic sense it is something that is easily recognised as trendy, and from a marketing standpoint innovators can thus claim new markets. Maybe it's because users of type don't feel confident (or can't afford to, in terms of time investment) to do these type of very graphic design laden experiments with type that they are comfortable with type designers picking colors and variations on their behalf - which makes this whole affair a tad bit more sad altogether.

Really good advice from the folks here. Thanks from my part for that.

This is vague, but my personal view anyway: You can think of a typeface as a person, someone with character, habits, quirks, manners, voice. I find it easier to imagine then which are ingenious and which are mediocre, and why so; which are interesting people to know and which will be shallow or boring soon enough.

And, please, take this humble learner's view with some critical reflection

In addition to the general sound advice already given, I also find myself playing around on letters that encapsulate the character of the typeface I work on. I don't mean to say start with something distinctive, but rather think of what are the essential features, and are there glyphs that really articulate those. But either way, always do basic n o H O's amongst the first.