I have been getting better. My current process is:
Apply thick layer buttercream, no crumb coat all the way around the sides & top. I use a squared off metal tool from Wilton. It's a dough scooper I think...but many ladies use a tool from the hardware store meant for plaster or spackle. I stand it up 90 degree angle, turn my turn table. Then, once sides are fairly smooth, I swipe in on the top of my cake. Sometimes I heat this tool in a pot of almost boiling water....dry and swipe. The heat smooths the sugar.
Let crust, then use viva paper towel & fondant smoother.
I have recently tried the upside down method. You should google it and give it a try. This method allows you to get super sharp top edges...which is where I was having trouble. It works with my regular buttercream recipe but not my chocolate recipe. Not sure why....
Keep practicing. Once you get your routine, it'll click and your progress will come faster and faster.