Action Details
Requirements and how-to articles for Etsy's action:

paid action
Offer free delivery or taking a percentage off of a listing’s price. You can run a sale on a single listing or on multiple listings.

You need this to get it done:

Choose the listing(s) you wish to apply your sale to.
Type of Sale
Choose what type of sale you'd like to run: percentage off (anywhere from 10% to 70% off the list price of items in your shop) or free standard delivery.
Minimum Order to Qualify
Choose the minimum order needed for your customers to be eligible for your sale: none (no minimum to qualify for the sale), quantity (number of items the shopper needs to purchase to qualify for the sale) or order total (minimum amount shoppers must spend at your shop to qualify for the sale.)
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

Etsy - Advertising & Marketing Policy
Etsy's official policy for advertising and marketing, which is part of their terms of use.
Etsy Help Centre - How to Set Up Sales and Coupons for Your Shop
Official information about setting up sales and coupons on Etsy.
Etsy - Organising a Productive Promotion for Your Shop
Official help guide for Etsy shop promotions.
Link missing here or found errors? Improve How-Tos