Keep them in longer.
If possible wear the twists for a few days or so to give your hair a chance to set more. The result is a more defined twist out that you can wear for a while. Please keep in mind that how long the style will last also depends on daily activity and maintenance.
Many naturals like to put their twist out in large twists while sleeping, then using a satin bonnet. If your hair is shorter you may need to re-twist at bedtime, unless you wore the twist for a while and they do not need it.
Taliah Waajid makes products that aid with achieving a great twist out that will last. You can try Shea-Coco Natural Hair Style Cream for 3C-4C Hair or Curly Curl “Gello” for hold and shine.
When you get to the end of the twist coil the ends around your finger. It helps to also fight the frizz when you do the twist out.
Too much separation brings on the frizz. Separate each twist into two sections, if possible, or up to four sections at the maximum.