There’s lots of useful stuff out there on this, and these links should help:
Goodreads for Authors
Joanna Penn on the Creative Penn
How to Market a Book and Strengthen Your Author Platform with Goodreads
How to run a GoodReads giveaway with maximal results: 11 tips we know you’ll need
Emlyn Chand on Novel Publicity, Co.
Marketing after a Goodreads Giveaway
L.A. Lewandowski on Indies Unlimited