eBay have put together this handy Guide for Growth which is the basis of their growth program. All new eBay sellers have the opportunity to participate in it.

Sellers can sign up here to be directed to a growth specialist. Sellers who participate in this program will usually see an increase in GMV/sales volumes compared to sellers who don't participate. 

The growth program is designed only for new sellers, but ALL sellers can use the attached guide to improve sales.