I am a beginner when it comes to working with fondant.
I have never used actual fondant , Just MMF. I get so frustrated because it never comes out the way I want , it always cracks ,or I can never get the fondant over the cake correctly.
I haven't worked with fondant enough yet to have a lot of confidence, but I'll give you some tips that work for me.
* Don't roll as thin as you want, thicker fondant cracks less.
* Powdered sugar not corn starch when rolling, use as little as needed to keep the fondant from sticking.
* Rolling on sheets of parchment paper has been a lifesaver for me. I need less powdered sugar so the fondant does not get dry so quickly, also I was able to flip the fondant onto the cake much easier than rolling up onto my rolling pin.
* Crisco is your friend when working with MMF. I recently did an 80's theme cake with lots of small fondant accents. I had 8 or 9 colors going and every time I stopped with one color I rubbed a coating of crisco over it and sealed it in a zip top bag.
* Short trips in the microwave will get fondant to a soft stage faster and it will exposed to the air less time to help prevent it from drying out.
I'm no fondant expert, these are just tips that have worked for me.
If you are making your own MMF please remember to use only the minimum amount of powdered sugar. I have never used all of the sugar that is asked for in the recipe. Use only enough to get a smooth, pliable fondant. Wrap it well and let it sit overnight. It will firm up. Then if you need more sugar knead it in then. Your fondant is cracking because it has too much powdered sugar. Work in a little crisco at a time. The amount of sugar that you use will vary every time that you make. Alot has to do with the weather and how humid it is. When you roll it out use a shaker with powder sugar. Covering a cake just takes some practice. Hope this helps.