The Wolfram *Workbench* provides a system of templates
for adding common fragments of *Mathematica* code.
Inside a *Mathematica* source file, enter
Ctrl+K. This should bring up the template
choices, as shown below.

You can add to the list of templates by using the Template page
of the *Mathematica* preferences.

Note that if you are using the Wolfram *Workbench* plug-ins without the
Wolfram product plug-ins, then the key sequence for command completion
will be Ctrl+Space. This is described in the section on
key bindings.