Corn starch will work, but I would try xanthan gum- it's readily available at grocery or health food stores.
Agave is a humectant, but is added to provide hold.
If you're sensitive to glycerin, like I am, I never have an issue with agave.
2C-3A/ Coarse/ Normal to high porosity/ SW Florida
Wash: CJ Daily Fix, AIA Coco Cowash, Trader Joe's TTT condish, Shea Moisture MRS
CO: CJ Smoothing, Curly Kinks Renew, Darcy's Pumpkin, CJ Curl Rehab, Regis Olive Oil
Enhancers: Okra gel, FSG, Uncle Funky's CM, CJ Pattern Pusha, KMF Upper Mgmt
I always top with a gel: MGA sculpting, Giovanni LAN, Spiral Solutions FHG, JC Spiralicious
Other loves: Coconut oil soaks & pre poo, Jane Carter N&S