Most symbol font sets come with a package that defines commands for every symbol in the font. While this is convenient, it can lead to difficulties, particularly with name clashes when you load packages that cover fonts which duplicate symbols — an issue which is discussed in “symbol already defined”. Some font sets (for example the related set: FdSymbol, MdSymbol and MnSymbol) are huge, and the accompanying macros cover so many symbols that name clashes are surely a serious problem.
The pifont package (originally designed to use the Adobe
Zapf Dingbats font) avoids this sort of problem: it requires
you to know the font position of any symbol you want to use (the
documentation provides font tables). The basic command is
\ding{number} for a single symbol; there are commands for
other fancier uses. Pifont also allows you to select other
fonts, for similar use.
The yagusylo describes itself as “an extended version of
pifont, gone technicolor”. It provides all the facilities
of pifont, but allows you to create your own mnemonic names
for symbols. Thus, while you can say
\yagding[family]{symbol number}[colour], you can also
define symbol names with \defdingname, and then use them
with \yagding*{symbol name} (the defined name carries the
font family and colour specified in the arguments of
\defdingname).
Yagusylo is somewhat complicated, but its documentation is clear; it is probably the best tool to use for picking and choosing symbols from a variety of font families.
This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=usesymb