Okay, just a bit of analysis, which may or may not clear somethings up for some people.
Seems that the method of cleaning might depend on the specific situation. From my experience, which is only a few months mind you, is the following.
If you have only had an atomizer a week, and your performance has gone down hill, chances are what you have is a liquid build up, so blowing it out, with your mouth, or a can of air duster should suffice, after you get the liquid cleared out, take it easy on the liquid if you are dripping, if you are using carts, not much you can do, but make sure a cart is completely out before you switch them.
If you have had an atomizer a few weeks, and your performance has gone down hill, you may only have a liquid build up, so try what is above first, if that doesn't work, what you probably have is, techincally speaking yucky slimey stuff in your atomizer that simply blowing it out won't pick up. So at that point, you are going to want to steam or boil, i think steaming may work best, but the biggest point is to get the build up wet, and hot, so that the slime dissolves, and is able to leak out of your atomizer. Whichever you choose, you are going to want to blow your atomizer out and let drain a bit afterward.
Oh, and if you have a really hot atomizer, don't blow into with canned air duster, as it will increase the chances of your atomizer dying during the cleaning process (i don't want to explain extreme temperature changes and its affect on stuff, but drop a few ice cubes into a glass of hot water, enough said). Let it cool down to wear it won't burn your lips if you are going to blow into with yourself, or just to touch if you want to use duster, but make sure to do short bursts so not to cool it down with the duster too rapidly, the time varies, so i didnt' want to quote a specific time.
Once you are done, you will probably have to use about twice the normal liquid, or take several extra drags off of your cartridge before you get consistant vapor, due to you having just completely dried your atomizer out, and even then, you may still feel some resistance for probably an entire cartridge, or about your 3rd or 4th "session", or whatever you want to call it, of dripping.
Not sure if this helps or hurts, but there you go.
B
Tried boiling and every other thing to no avail and was going to right it off as a learning mistake. On my shelf was a bottle of Pipe Sweet. Its used to clean out your pipe when it gets sour tasting from use. It removes all the tar build up and gunk from the stem and shaft and leaves a fresh taste. 
