Today we're going to start at the very beginning (a very good place to start). Try introducing a writing instrument to your child around 9 months of age. (That age was recommended to me by my Parents as Teachers Organization as well as my pediatrician. However, Logan did not start holding the crayon and making marks alone until around 1 year).
There are many choices of writing instruments. There are triangle shaped crayons, rounded crayons, etc. Most children don't need a special type of writing tool when beginning. A plain crayon will do. If your baby eats the crayon, try these colored pencils. They are chunkier so they feel more like a crayon but they can go in the mouth.
One of our favorite beginning activities was making large marks on paper. Guide your child's arm around at first and demonstrate making large circles/scribbles. Say, "We are making large circles. We are making green circles.)" etc.
By exposing your child to scribbling at a young age, you are helping to develop the hand-eye coordination, fine motor skills, creativity and enjoyment that your child will need to be a writer in the future!