As you may already know, [mathematica.stackexchange](https://mathematica.stackexchange.com/questions) is a wonderful site for asking questions and looking for information about Mathematica™.

However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users producing questions that are difficult to read and/or answer and diminishing the site's overall usefulness.  

Many hints and software pieces have been posted on these sites over time explaining or solving individual issues that we may try to recap and summarize here.

This question is intended to be a link reference for users that composed non optimal posts instead of explaining the reasons and solutions each time. 

Please help me to identify and/or explain those pieces of information that help and guide users to get the most from the site.

Suggestions for posting answers:

* One topic per answer
* Focus on
	+ The most common mistakes people make when posting questions
	+ The most useful ways to get a problem solved using the info already posted on the site
	+ How can new users help on maintaining the site clean and useful
* It's OK to include a brief explanation and a link to another already posted question or help page
* Include a self explanatory title in h2 style
* Include a link to your answer by editing the **Index** below (for quick reference)

Index
-----

* [### Search the site before asking](https://mathematica.meta.stackexchange.com/a/1480/193)
* [### Formatting your Question](https://mathematica.meta.stackexchange.com/a/1481/193)