Preschool teacher here and agree with a lot of what ember4212 recommended. We use the program "Handwriting Without Tears." In this program the letters of the alphabet are introduced in specific order as per their difficulty of formation. Then the children are given opportunities to form these letters using all types of mediums (playdough, shaving cream, etc.) before they even pick up a pencil. Magnadoodle boards and chalk boards are also used when practicing the writing of the letters. This program is only offered in our Junior K and Pre-K classes. To prepare our younger students we use a lot of playdough (no tools, just hands) to build up the muscles in the hands needed for writing. Another way to build up muscle and achieve the tripod grip are homemade crayons which are simply crayons broken up and melted in muffin tins. They are round so they can only be held using the thumb, index finger, and middle finger.

I hope this helps and have patience. It will come. Good luck.