Master these two methods to add to your repertoire
Slip Stitch Seam: place the crochet pieces right sides together. Insert hook through both edge stitches yrh and pull through to complete 1 sl st; rep from working loosely.
Double crochet seam: place the crochet pieces right sides together or wrong sides together for a visible seam. Work as for slip stitch seam but using dc instead of sl st.