A minimal example1 is the smallest possible complete document that illustrates a problem. A minimal example file should not include any packages or code that do not contribute to the problem, but must include a document class and the document environment.
There are two approaches to creating a minimal example: “building up” and “hacking down”. This document illustrates both approaches. Creating the minimal example may lead you to the solution, but if you are still stuck, you can then post the minimal example. (Remembering first to search for the solution in the documentation and on the Internet, for example, in newsgroup archives or on forums or Q&A sites.)
Some package authors (including me) from time-to-time2 read messages on sites such as The LaTeX Community, TeX on StackExchange or on newsgroups such as comp.text.tex, so if you have a problem you can't solve it's generally a good idea to post your query in one of those places (remembering to paste the contents of your minimal file in your message). If you've made a mistake in your code, then someone may be able to point it out, which may mean that you get a reply quicker than you would if you posted your query directly to the author. Also, other people will be able to see your query and learn from it. Remember that no one is being paid or is otherwise obliged to answer your query, so be careful not to make your query sound like a demand or an accusation.
Note that when posting your query, you also need to give a brief description of the problem, and list the methods that you have tried to trace the problem. Don't go into a long rambling description of your project, as it generally doesn't help to identify the problem, and too much information can put people off reading your request. It's also a good idea to first search the comp.text.tex archives or use the search box on sites like The LaTeX Community, TeX on StackExchange to find out if anyone else has asked the same question. If you ask a frequently asked question, you may get a curt reply from people who are tired of answering the same old question, so check first.