Now, I've only iced/frosted 2 cakes to date with home made bc. I'm just having a terrible time with it! My first cake was ok but my second cake just looked horrendous! When I am icing a round cake I can't get the edges to look good. I use the icing tip and I start in the middle of the cake going in a circle towards the outside. I over lap the edges, then do the same on the sides. When I start smoothing it, the top icing goops to the sides, then once I do the sides it pushes it back to the top!! GRRRR!
Also, I don't think my icing is a good consistancy. It doesn't seem very fluffy... I don't know. I guess I just need practice, I'm just frusterated because when my teacher iced her cake she made it look so easy! 
real buttercream icing is wonderful stuff. but it is very tempermental. It has problems with the weather and climates. one thing you can do for fluffiness is replace using milk with whipping cream this will give you a fluffier icing. for stiffness add a teaspoon of cornstarch a little at a time.
Shadowgypsie
Do you crumb coat first?? and how stiff is your BC?? Do you use the wilton recipe?? There are alot of factors to think about. You also don't want to lift your spatula straight up when icing a cake. These are some of the things to think about. It took me awhile to figure it out. My girl scout cake had alot of icing on it. I bet the girls had a sugar high after that one. I had only done course 1 and still new. Boy thinking back there was ALOT of icing on that cake 
Just keep practicing and asking ????
remember that when you are using the large wilton icing tip you are going to put more icing on than you will actually need. when you use your spatula to smooth the sides and then the top you will remove the excess and put it back in your bowl. by removing the excess you shouldn't be pushing it up or down.
Thanks guys... I've come to the conclusion that it's just practice makes perfect and I'll get it in due time!!
As for the recipe, I've been using the wilton recipe, as well as a recipe from this board, but it made sooo much that it was really difficult to work with! I usually do 1/2 butter and 1/2 crisco as I've got terribly hot hands and that seems to have helped.
I don't crumb coat... I didn't think you had to do that with BC.
When I ice I go with the big tip in a circle leaving some icing hanging over the edge. Then I Put my angled spatula in the center on an angle and I turn the turntable lightly pushing down so the icing bulges over the sides a bit. Then I do the sides of the cake... This is where my problem happens. It seems to push the extra back to the top of the cake. Maybe I'm not angling properly. I dunno!
Quote by @%username% on %date%
%body%