Sample preparation can be an arduous task, and it often seems like success is as dependent on the weather as it is on your procedure.  Here are some helpful links for determining polishing procedures. This is in no way endorsing the products of this company but they did provide free training documents.

Metallography procedures for some common materials

Etchants for some common materials

A more complete Metallography Manual

A Conversion chart for comparing consumables using either the U.S., European, or Micron Grading Scale: