Well I'd decorate my altar with autumn leaves and pomegranates. I'd also go for long walks in nature( prep for the coming winter and craft ways spiritually) reflecting on summer and what you'd like to do for the winter. During the walks collect nuts and berries to preserve a d apples to dry because is there no fresh produce. A prayer: "Let us give thanks from our heart For all the blessings of all our good harvest For the hard-won lessons of life For the people who bind us together Making joyful warm hearts out of strife." i suggest the book "The Green Wiccan Year" by Silja. It has helped me understand the meaning behind Sabbats and how to celebrate for them. I strongly recommend it:) hope this helped!