Quality of PDF from PostScript

Any reasonable PostScript, including any output of dvips, may be converted to PDF, using (for example) a sufficiently recent version of ghostscript, Frank Siegert's (shareware) PStill, or Adobe's (commercial) Distiller.

But, although the job may (almost always) be done, the results are often not acceptable: the most frequent problem is bad presentation of the character glyphs that make up the document. The following answers offer solutions to this (and other) problems of bad presentation. Issues covered are:

It should be noted that Adobe Reader 6 (released in mid-2003) does not exhibit the "fuzziness" that so many of the answers below address. This is of course good news: however, it will inevitably be a long time before every user in the world has this (or later) versions, so the remedies below are going to remain for some time to come.

This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=dvips-pdf