LaTeX2e has a standard package for graphics inclusion, rotation, colour, and other driver-related features. The package is documented in the second edition of the Lamport's LaTeX book (see TeX-related books), and is available in macros/latex/packages/graphics
If you don't use LaTeX2e, perhaps the best method is to use
the psfig macros written by Trevor Darrell, available in
graphics/psfig
You will also need a DVI to PostScript conversion program that
supports the \specials. The drivers mentioned in
DVI to PostScript programs do, and come
with a version of psfig ready to use with them. The psfig macros
work best with Encapsulated PostScript Files (EPS). In particular,
psfig will need the file to have a BoundingBox (see Appendix H of
the
PostScript Language Reference Manual). If you don't have an EPS
file, life can be difficult.
One point to note about including PostScript figures is that they are not part of the DVI file, but are only included when you use a DVI to PostScript conversion program. As a result, most DVI previewers will simply show the blank space TeX has reserved for your figure, not the figure itself.
There are two rather good documents on CTAN addressing of figure production with rather different emphasis. Anil K. Goel's, info/figsinltx.ps covers the different ways in which you might generate figures, and one the old (LaTeX 2.09) ways of including them into documents. Keith Reckdahl's, info/epslatex.ps, covers the standard LaTeX2e facilities, as well as some of the supporting packages, notably subfigure (macros/latex/contrib/supported/subfigure) and psfrag (macros/latex/contrib/supported/psfrag).