AJust wanted to start a thread where people can give tips and tricks for how they achieve the perfect fondent covered cake :)

AMy tip would be get good quality fondant. I tried making my own but it's just difficult to work with so I suggest the brand Satin Ice.

1. Level, straight sides cake.

2. Smooth buttercream or ganache layer

3. Mist slightly

4. Cover with fondant

Fondant DOES NOT cover mistakes in the underlying structure. Work with a little thicker fondant to help "learn" the feel of it, then you can go thinner (and cheaper). 

Fondant requires kneading to make it workable. Work with premade fondant until you get the feel of it, and then you can try to make your own. 

What Johnson said- fondant doesn't cover rough buttercream/ganache, so getting that smooth from the beginning will help make fondant look smooth. You'd have to roll fondant pretty thick- IMO over 6mm thick- to sucessfullly cover unevenness in the fondant.

Fondant itself is key- there are brands that just fall apart as soon as you place it on a cake, brands that are dry and cause elephant skin, and brands that do both. You'll have to buy several brands to see which you are happy with.

Creating a 'curtain'. I know there are decorators who can cover a cake with fondant that is almost the same size as the cake. I am not one of them. I need fondant that is rolled to a size that when it goes on a cake, there is excess all around the bottom of the cake and beyond. I pull the curtain as I go round smoothing the fondant to prevent folds.

Smoothing technique. In the beginning I wasn't firm enough with my smoothing. I've since learned to press harder with my smoothers, but not so hard that it makes marks. Also, getting a ball of fondant, the same colour as that placed on the cake, and using it as a smoother is a fab technique.

If you still have the odd mark here and there- make gunge. This article was really helpful:

http://ericaobrien.com/blog/gunge-its-a-miracle/

If all else fails, you can only hope that the client has asked for decoration!

ADo you guys have any suggestions for making a buttercream or ganache coating?

The Mat! Perfect fondant topping every time.

http://sweetwise.com/the-mat-all/the-home-mat.html

ARoflmao, I've been using "gunge" since I started with Fondant. I have only done about 15 Fondant cakes, as I'm just a home Baker. Who knew, it was an actual thing. I only thought to do it because of the fact that I own a painting company. I use drywall mud/spackle on the daily. Since I was new to Fondant, I HAD to come up with something to fix all my mistakes, lol.

And how many years have I been redoing fondant on cakes because of elephant skin, nail marks, etc.?  I've never heard of this before, but I can guarantee that I'll be using it now.

Thanks a million!

Thanks for the gunge tips. I will be trying this fix-it method next time.

When I think of "cake spackle", I think of the Toba Garrett method to repair cakes which have chunks missing (before crumb coat or frosting or fondant).  Sweetwise has done a very nice 2 minute video to illustrate this:

Repairing Cakes With Cake Spackle by www SweetWise com

I guess I'll think of the new fondant repair trick as "fondant spackle".  It's ALL good!   Thanks everyone; I love this cake community.