If you store custom templates in Outlook folders you'll have easy access to the template and won't need to browse the Tools, Forms, Choose Form menu looking for the template.

After choosing File, Save as and selecting Outlook template, note file location. Find the template using Windows Explorer and drag and drop it into an Outlook folder. When you need to use the template, find it in the Outlook folder and double click on it. As an added bonus, when you backup your mailbox, since the templates are stored in the mailbox, they are backed up too.

Tips:
Create a Mail and Post type folder called Templates to store your templates in.
You can store templates for all Outlook item types in this folder.