Tracing pages will make it easy for children to learn how to trace. Prior to learning to print and write correctly a child needs to be able to master a pencil. Tracing lines gives a child plenty of practice.
Typically children find these worksheets fun and challenging at the same time. It's best to teach children the correct way to hold a pencil prior to teaching any actual letter writing.
If your child is having difficulty, try using a golf pencil which is shorter and wider. Or use a pencil that has been repeatedly sharpened so it is only about half as tall as a new pencil. Kids have a much easier time with a shorter pencil.
Start with the straight lines, then move on to the curved when your child is ready. There are also combination worksheets that have both straight and curved lines.
Prior to using tracing pages children should have plenty of experience using writing utensils. Let them use a wide variety (pencils, markers, chalk, etc.) while they are still in the scribble stage.
At the ages of 2-3 children will hold a writing utensil with their whole fist. Typically the instrument is grasped with the pinky finger closest to the paper.
Holding a pencil correctly typically comes between the ages of 4 and 7. Until a child understands how to correctly hold a pencil it will be difficult for them to learn to trace.
Here are some ways to help teach a child this important step...
Give your child a cotton ball (or another small and easy to hold object) and have them hold it against their palm with their pinky and ring fingers. This keeps a couple of fingers occupied while the pencil is being held with the other three fingers.
Show them how to hold the sharpened end of the pencil between their thumb and index finger and let the pencil fall back into the webbed area between those fingers.