Adding finished size(s) and/or measurements is important for the customers to build up an expectation for the pattern. If you have ‘one size only’, add measurements to help the customers build a picture of the finished result. For customers who like buying yarn and patterns at the same time it makes it easier for them if you link to the yarn. Patterns with linked yarns also show up on the yarn page, increasing your pattern’s visibility.
When suggesting yarn, each colour should be added on a separate line, but suggesting 2 or more different alternatives has proven to be more confusing than helping, one yarn has been proven to work best.
For tips on how to display sizes and measurements in your patterns, read Kate Atherley's blog post here!