Glycerin is great for retaining moisture that is already in your hair. The problem is that it will draw moisture out of your hair to itself. So only use it when your hair is damp and you may need to spritz up your hair again several times a day to keep it soft if you are in an air-conditioned or dry enviromnet. The more humidity, the longer your hair will stay moisturized.
With this recipe, you can double the proportions of oil & glycerine if you wish, but keep honey low. This mixture will last 2 weeks and a little bit longer if kept in a dark bottle and cool.
1/4 litre chamomile tea
1 tsp honey
2 to 3 tsp glycerine
2 to 3 tsp of your favorite carrier oil
3 to 6 drops essential oil (3 drops rosemary, as a preservative + 3 of lavender or just 6 rosemary oil)