Preschool is the time to start teaching handwriting. A friend sent me a great file related to the Handwriting Without Tears program that gives ideas for teaching kids how to form letters. If you'd like to try utilizing these letter formation ideas into your curriculum, you can check out the files at http://www.scribd.com/doc/18372778/Handwriting-Without-Tears-Chart
My suggestion for beginning writers is to avoid the structured handwriting tablets frequently sold in stores this time of year. I focus on using the tablet once my child has the basics for each letter down pat. I use a dry erase board and markers to teach letter formation. I prefer starting with a dry erase board and letting them free form their letters by using letters I've written as a guide.
After the Christmas break, when they have all their letter formation and recognition down pat, I move on to the structured writing tablet. I also like the dry erase board because it's just fun. We have a large one that allows us to lie on the floor and write together. Another idea is to buy small dry erase boards and write in your lap. You can even play a game where you call out a letter to draw, hide the board while you're writing the letter and then flip it around to show each other your letter. Kids like this because it has an element of surprise. Happy homeschooling!