I've used a bit of Epsom salt dissolved in water (about 1/2 tsp of the solution), I read that it's a curl enhancer...last time I added also 1/2 tsp of olive oil, for moisture?
I like these two, along with honey in the basic recipe

Type: 3a
Dense, fine/medium texture, low porosity

Low-poo: Devacurl No-Poo/ Yes to Carrots Nourishing Shampoo/ Elacel Aloe Vera Shampoo
Conditioner: Garnier Fructis Triple Nutrition Conditioner
Leave-in: Devacurl Set It Free/Lush R& B
Styling: Herbal Essences Set Me Up Spray-Gel/ L'Oreal Silk & Gloss Curl Power Mousse