I buy forms at Dollar Tree and sometimes my ribbon. I feel like a wreath that is full is much more attractive so I like to flesh them out. Sometimes I use flowers. Christmas I add miniature ornaments. One of the most fun wreaths I've made is this summer beach themed one. It cost $5.
Here's one I posted for Fall - https://www.hometalk.com/31122200/unbelievably-easy-fall-burlap-wreath
And another that will work anytime of year - https://www.hometalk.com/43429004/easy-diy-hydrangea-wreath
ideas & videos https://www.youtube.com/results?search_query=diy+diy+wreaths