For information on making dovetail templates, see our beginner site Common Woodworking.
I have used this dovetail template for 45 years. I have used others too, bot none come close to this one for ease of use and quickness. The steps for making it are simple. You can have one done in about ten minutes. Accuracy is critical because every dovetail you make in the future will rely on the lines that follow the guide. You can make them with different angles but I usually use only a 1-7 ratio unless I am working on a restoration project. Any wood, including pine, will work fine and because no knife or metal tool touches it, only a pencil, it will last for your lifetime as mine has.
I’m preparing the steps to show how it’s done, for those who haven’t got my book. I have another booklet, not yet published, on making different types of templates I’ve taken from templates from the 18-1900’s