The CEC published an article by Dominique Bassal, on mastering in the
context of electroacoustic music- find it here: cec.concordia.ca/econtact/
(follow the link to edition 6.3, 'Issues in Electroacoustics'). The original
is in French, but there is a translation available.
A quick summary of some of the important points-
-mastering involves frequency and dynamic sculpting, for which eqs and
compressors/expanders are the tools 'par excellence';
-over-compression has seriously degraded the sound quality of most
commercial pop music recordings, but some degree of compression can still be
appropriate for experimental music, depending on circumstances;
-mastering may also involve, occasionally, spatial treatments to widen the
stereo image or create a sense of acoustic;
-it is very difficult to master your own work, especially in the studio
where it was produced- you'll probably end up exacerbating the frequency
problems in your mix, by overcompensating for monitoring deficiencies. I'll
post more on this later,