Paul

You may choose a colourful style for the custom coupon message, or wrap the message in your own CSS class container.
It’s also possible to hide the default message from Woocommerce so that only your custom coupon message is displayed. 
(the plugin uses inline CSS to hide the default Woocommerce message).
Take a look at the screenshots for the coupon edit screen with the plugin enabled and some examples.
The meta box was implemented using the technique described on this blog post: 
http://wp.smashingmagazine.com/2011/10/04/create-custom-post-meta-boxes-wordpress/
The message styles were generated using this tool: 
http://www.bestcssbuttongenerator.com/

Woocommerce Custom Coupon Message

This plugin adds a meta box to the coupon edit screen where you can make your own customized coupon message.

GauravNagpal

Less sold products with special attributes and tags can be sold easily using this feature without affecting sales for popular products. WooCommerce coupon section extension for adding coupons for special attributes and tags.
After enabling this plugin, you will see a new multiple select box in the coupon “User Restriction” section. All the other preferences will not be affected; it will work perfectly as it was before.
<ul>
<li>Work for both attributes and tags</li>
<li>Coupon categories</li>
<li>No new section for coupons</li>
<li>All other existing features will remain the same</li>
<li>Can be clubbed with other WooCommerce coupon rules</li>
<li>Can be applied percentage or a flat amount on products</li>
<li>Supported variable and simple product types </li>
<li>Attribute created in “Products > Attributes” tab are supported</li>
</ul>
If you like this easy plugin and if the plugin is improving your sales, then <a href="https://www.paypal.me/gauravnagpal" rel="nofollow ugc">Donate</a> a little to this development time or at least spend a couple of minutes for feedback.

Attributes Coupon for WooCommerce

WooCommerce coupon section extension for adding coupons for special attributes and tags. Also, you can categorise the coupons.

Woocommerce Custom Coupon Message vs Attributes Coupon for WooCommerce