Apply a light amount of finishing serum to hair around face and up to the CharlieCurl to lay down flyaways and to moisturize what will be an under layer, so that hair will lay better.
Leave in overnight or for a minimum of 3 to 4 hours.
If your hair is hard to curl or you lose curl easily, your hair is probably very round-ish in shaft structure. Think of curling up a garden hose rather than a strip of paper.
Curl hair when damp:
Curling happens most easily in straight hair because the cell structure reformats when hair is wet.
Hydrogen (H) binds the cuticle to the cortex (the outer layer to the inner layer of hair).
When broken by additional H from water (H2O), the bonds reform in the shape they dry in.
This is why when you dry your wet hair in one shape, it will basically stay that way. When set wet, the hair structure tends to stay, but will reshape toward its natural straight form over time. Also, this is why damp weather causes hair to straighten faster.
If hair is healthy and cuticle is strong and sealed, curls will last longer.
Don't forget - setting gels and hair spray can be experimented with for more hold.