After having work on some big projects using very strong naming conventions, I recognized that despite of the boring aspect to “force yourself” using a specific convention, it is much more readable when you read code written by someone else.
Here are listed the choices I made while developing Sandy, and which is the one you'll have to use for your contributions.

All classes name are written in English.
They start with a capital letter, and basically use the Java naming convention.
Interfaces shall start with a capital I.
Abstract classes (even in not native in ActionScript) shall start with a capital A.

Variables also require a specific naming convention.
Scope information:

• Local variables starts with “l_” prefix.
• classes protected/private members use “m_” prefix.
• parameters use “p_” prefix.
• global variables use “g_” prefix.
• static variables, use a capital and explicit name.

The exception is for the public class members, that don't use any specific prefix.

Type information:

• numerical variable use the “n” letter (Number, int, const, uint).
• arrays are defined with the “a” letter.
• objects are defined with the “o” letter.
• interfaces are defined with the “i” letter.
• movieclips are defined with the “mc” letter.
• events are defined with the “e” letter.

Names : Once the prefix written, comes the real name of the variable. Even if the actionscript code is faster at execution time when variables names are shorter, we recommend to use explicit names. Sure the shoter explicit name is better.
The attention required for the variable name also depends on where it is used. The more critical and complex location, the more complete and explicit the variable name should be.

Example :

• Local number variable definition :

var l_nMyNumber:Number = 0.33;

• Local array definition :

var l_aMyArray:Array = [1,2,5,7,12,19];

• class definition :

class MyClass
{
    private var m_mcContainer:MovieClip;
    public var version:Number;
 
    public static function main( p_mcRoot:MovieClip ):Void
    {
        var l_oInstance:MyClass = new MyClass( p_mcRoot );
    }
 
    public function MyClass( p_mcRoot:MovieClip )
    {
        m_mcContainer = p_mcRoot;
        version = 2.0;
    }
}

Sandy conventions also require to always specify the whole scope of the variable/method in the classes definition.
Example :
Bad declaration of MyClass example

class MyClass
{
    private var m_mcContainer:MovieClip;
    var version:Number;
 
    static function main( p_mcRoot:MovieClip ):Void
    {
        var l_oInstance:MyClass = new MyClass( p_mcRoot );
    }
 
    function MyClass( p_mcRoot:MovieClip )
    {
        m_mcContainer = p_mcRoot;
        version = 2.0;
    }
}

In addition to the naming convention, Sandy developers shall use the following development rules :

• bracets shall be after a new line.

Correct example :

function test( p_bMyBoolean:Boolean ):void
{
   if( p_bMyBoolean )
   {
       ;// Do something here
   }
   else
   { 
       ;// Do something else
   }
}

Wrong example :

function test( p_bMyBoolean:Boolean ):void{
   if( p_bMyBoolean ){
       ;// Do something here
   }else { 
       ;// Do something else
   }
}

• Each function/method shall specify their return type. Every variable shall be type correctly (see specific chapter on that subject for more information).
• Method/function shall provide some JavaDoc documentation style.
• Classes/interfaces shall provide a JavaDoc documentation style.