With crusting buttercream, I have been using Melvia's method of foam paint roller. It works great. I bought a large for top of cakes and have a small on for smaller sides.
See link:
http://www.cakecentral.com/cake-decorating-ftopict-42675-share.html
Judy
I learned to use the hot knife method and apply a bit pressure. Always wipe off knife and redip in hot water then rewipe and smooth again.
Gracy, after your cake crusts, take a Viva paper towel and just use the palm of your hands. Trust me, I was having an awful time also, and this method is really the best so far. The Viva paper towels have no design on them so that will be what provides your smoothness. I have used paper towels that have a pattern, and it sometimes adds a nice little touch to the cake. HTH and good luck!!
p.s. Don't give up...just keep trying..you'll get it right, trust me!!
Try Melvir's foam roller method, it works like magic. Here's the link to the post http://cakecentral.com/modules.php?name=Forums&file=viewtopic&t=42675&postdays=0&postorder=asc&&start=0 I used the viva paper towel method until I tried the roller and now it's all I use. It's truly amazing.
After I frost my cake I let it sit to get a crust. When I know that my frosting doesn't stick to the parchment paper or wax paper, then I smooth it. This is what I show my students when I teach the Wilton class. Sometimes I find it easier just to use wax paper. Do you use the spatula or the icing tip to frost your cake? Are you also using a turntable too? When I use the wax paper , it is really to just get my frosting smooth with out any lines. Hope this helps.
Monique
I use the buttercream dream recipe and ice my cake with a paint spackle. Then after it crusts i use my finger to smooth out the seams. I have read that a foam paint roller works miracles but, I have not tried it.
hi gracy, welcome to CC!
when you tried the parchment paper smoothing did you allow the buttercream to crust before you applied the parchment? if not, give that a try.
also, if you're dipping your spatula in water, make sure the water is nice and hot.
there are a couple of techniques on this site that are a little bit different that you could try:
1. Upside down icing technique http://www.cakecentral.com/article6-Upside-Down-Icing-Technique-for-Perfectly-Smooth-Icing.html
2. Foam roller technique - do a search in the forums for it.
First I got the big metal scraper, I guess like a spackling knife from the hardware section-a big one. After you put on a thick coat of icing (I usually use the icer tip, but not always) I then boil water on the stove and dip in the scraper. Sometimes I dry it, sometimes I dont, Ihavent figured out what I like best yet. Then I try to get the top pretty smooth, then I go onto the sides. I put the scraper at about a 45 degree angle and turn the turn table. Try not to stop turning until it gets all the way around. (see how they do it in the upside down icing technique in the articles) It will be very smooth. then I try to bring the extra icing from the side near the top over to the top of the cake. Then I use the viva method on the top(after it crusts) I like viva paper towel over parchment paper for smoothing. I use the fondant smoother on top of the viva and sort of iron it. I try not to viva the sides if possible, because I think it is smoother after the hot knife (spackler) technique. I havent tried the foam roller, but I know a lot of people are liking it. I still think smoothing is the hardest part of decorating so far! but I am starting to finally get the hang of it.
There's the Viva paper towel trick and Melvira's sponge roller trick, which can be combined.
Also b/c tips and other frosting tricks.
Here's a thread:
http://www.cakecentral.com/cake-decorating-ftopict-45089-.html
http://www.cakecentral.com/cake-decorating-ftopict-42675-.html
http://www.cakecentral.com/cake-decorating-ftopict-19948.html
http://www.cakecentral.com/cake-decorating-ftopict-1353.html
http://www.cakecentral.com/cake-decorating-ftopict-27876-.html
The foam roller is the BOMB! 
I used to use parchment paper or the hot knife technique, but my cake didn't always turn out even. The foam roller does a great job. just be sure to let you icing crust for about 30 minutes. 
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