Coding conventions

Formatting

Always put a space before and after a binary selector, as well as inside blocks.
Name method arguments like aFoo and not foo.
Name temporary variables and instance variables like foo and not aFoo.
Properly indent your code using tabs, not spaces.
No unnecessary parenthesis.
No unnecessary blank lines, except after the method comment, temps declaration, long methods (>= 5 lines) or 'guard' statements, such as shouldReturn ifTrue: [ ^ self ]..
Always use yourself in cascades.
Use each as an argument name of iteration blocks.
Add a space at the beginning and end of a temporary variable declarations and blocks.
Avoid unnecessary statement separators.
Close multiple blocks on one line, exception can be made for #ensure: and #on:do: blocks
Keep methods as short as possible (up to ~5 lines is ok).

The first comment of a method should state the use of the method. Keep it short, but ensure that these are valid sentences starting with an uppercase letter and end with a full stop.
Avoid comments within the method body when not needed or intention revealing.
Class comments are mandatory
Referring to Github issues is OK in method comments, but not in class comments.

Do not create classes with methods on the class-side only, instead think of another approach oe use the singleton pattern instead.

#initialize should always send super initialize
When using initialization methods other than #initialize, do not send self initialize.
Constructors must send #new and not #basicNew to ensure object initialization

Use self assert: actual equals: expected instead of self assert: actual = expected where possible

(This page is freely adapted from Seaside coding conventions