Improve your users' overall experience by following these guides for add-on design.
General best practices
You are encouraged to follow the following best practices for all add-ons you develop.
Determine add-on ownership before starting
Add-ons are defined by Apps Script projects, which must be owned by a specific account or else placed in a shared drive. Before coding an add-on, determine what account should own the project, and what account acts as its publisher. Also determine what accounts are to act as collaborators, and make sure those accounts have access to the script project and its associated Cloud platform project.
Extend G Suite, don't replicate it
Add-ons are meant to provide new capabilities to the G Suite applications they extend, or else automate complex tasks. Add-ons that merely replicate functionality already within the application or ones that don't make significant improvements to a workflow aren't likely to pass add-on review for publication.
Avoid relying too much on libraries
Using Apps Script libraries can cause your add-on to run more slowly than it would if all the Apps Script code were contained within a single script project. Although Apps Script libraries work in add-ons, you may run into performance reductions if you use them. Avoid including unnecessary libraries in your project, and consider ways to reduce your add-on's reliance on them.
Editor add-on best practices
The following best practices only apply to editor add-ons.