I have would be interested to hear members tips for getting a totally smooth finish with fondant - is it as simple as the kind of fondant you use or the icing or ganache under the fondant or the smoothness of the cake in the first place. Please don"t tell me the obvious. Thanks so much in anticipation.
I always use ganache under fondant on big cakes, and I know with that you have to get the ganache perfectly smooth if you want the fondant smooth...any bump in the ganache will still be there when covered in fondant. Using smoothers (rather than hands) to smooth the fondant on helps too. I'm not a pro though, but I'm sure others will chime in here with their expert knowledge for you!
I suggest a perfect canvas underneath. So of course the crumb coat has to be pretty smooth. Also the trick is to roll your fondant as fast as possible and work quickly so it doesn't start drying and cracking. Also when smoothing the fondant on the cake work from top to bottom of the cake making sure you adhere the fondant to the buttercream underneath, if not it will have air pockets. If you do get air pockets just prick them sideways with a corsage pin and then smooth out the bubble with your hand. It leaves such a tiny hole you won't be able to see it. Also do this right after you put the fondant on if you wait then when you try to smooth it out it will crack the surface of the fondant :O.....been there done that lol!
I am a professional fondant decorator at a local bakery and I am still learning constantly! Have fun!! It just takes alot of practice! And I always use Satin Ice fondant!