Here are some tips:
* Use a doll-sized straightening iron: Regular-sized irons are too hot and can damage doll hair. You can find doll-sized irons online or at specialty doll stores.
* Use low heat settings: Always use the lowest heat setting on your iron.
* Work in small sections: Divide the doll's hair into small sections and work your way down each one.
* Use a heat protectant spray: This will help protect the hair from heat damage.
* Avoid using hairspray: Hairspray can make doll hair stiff and difficult to style.
* Consider alternatives: If you're not comfortable using heat styling tools, try braiding the doll's hair overnight to create waves, or using a doll-sized curling iron to add curls.
Important note: If you're unsure about how to straighten your doll's hair, it's best to consult a professional doll repair person. They can help you to safely and effectively style your doll's hair.