It's all about catering to your tastes. Add as much sugar as you like. I'll show you below, what I used, but the only thing that you need to have, is lemon juice. It will preserve the color. You may not need as much as I used, But I like to eat my fruit leather when it looks like the actual fruit that is in it! No black strawberry fruit leather for me!!! You can use other fruits with this same recipe. Some fruits don't require lemon juice but most do. So when in doubt, add it.
You could also speed things up by sticking it outside in the summer heat, and blow the fan on it (to mainly keep bugs and dust off as much as possible.
Also, don't make your layer too thick. I did a pretty thick one not realizing it and it took about a week to dry! Granted, I put my wimpy table fan on it, so that had a lot to do with it. My other one didn't take nearly that long :)
Strawberry Fruit Leather
5 lbs of strawberries
3 cups sugar (or desired amount for sweetness)
5 tbsp lemon juice (fresh or bottled)
Pour all ingredients into a pot. Boil for about 15 minutes, until fruit is cooked through. Pour into a blender and blend well. Lay long strips of plastic wrap on counter top. (Or you can line cookie sheets with plastic wrap) Pour a THIN layer of fruit onto the plastic wrap covering as much as needed. Place a high powered fan at the end of the line of plastic wrap so that it blows all the way down to the other end. Allow the fan to blow on the fruit until dried. (about 24 hours depending on thickness, humidity etc) The closer areas to the fan will obviously dry out faster than the ones further away. When dry, cut into desired size pieces and roll up. Store in an air tight container.
Tip: if using the oven, make sure that you have plastic wrap that is oven safe.