This will be the first time making ganache and putting it on a cake, so I'm wondering what you use to make the fondant stick to the ganache?

I lightly mist the ganached cake with a spray bottle (on mist setting, not spray or jet setting!), containing cooled, boiled water. Others just brush the water on too. Ensure your tiny amount of water covers all areas of your ganache, otherwise you it will not stick properly and you will spend a good few minutes popping air bubbles with a pin (ask me how I know ).

Oh dear, those pesky bubbles! I've had problems in the past with bubbles when I'd put fondant on buttercream, finally I learned to not put it on a cake that's been in the fridge for 6 hours.... Definitely want to avoid the bubbles! Off to get a spray bottle! Thank you!

I typically rub mine with a light coating of shortening...

I would think that ganache would be sticky enough for the fondat to ahere to it.

So I started using ganache under fondant, and got a major bubble issue. First I tried vanilla vodka lightly spritzed on to attach the fondant... major bubbles, twice. Second, I tried water lightly spritzed on... major bubbles, 3 times. Last I tried a thin coat of shortening I rubbed between my hands then rubbed onto the underside of the fondant before attaching... only 1 bubble! My vote is definitely for shortening.

When you mist the ganache, no matter how careful you are, it will bead up to a certain extent. This allows more air to be trapped under the fondant. When you rub shortening on the fondant, you're getting a more even coating and less air, so fewer bubbles to deal with.

I use a pastry brush to apply a thin coating of shortening. I find if I have to lift the fondant off that it doesn't leave any ganache on the fondant so I can reknead if I have to.

Thank you everyone for this.  I also made my first ganached cake today.  A two tier.  I don't think I will ever buttercream again it looks so superb (though costly!).  I covered the first tier and used the syrup recommended by Planet Cake.  Apricot jam, mixed with boiled water and strained.  Air bubbles galore.  I read the posts and used a thin layer of Crisco on the second layer.  Completely adhered, hardly had to use the smoothers and not one air bubble.