I've found a lot of it is compositional. I find it easiest to start with some sort of very simple sketch or color composition, then downsize it to see if it works. If not, I rework it-- it's just tricking the viewer's eye into seeing the right thing as if from far away.

I think Kesame/Sullivan has a nice variety of simple busts and almost full body/scenery icons here:
http://sullivan.deviantart.com/gallery/

Sorry, here is a link to all of the gallery:
http://sullivan.deviantart.com/gallery/?catpath=/

thank you very much, I really appreciate it.

This is very, very helpful information regarding making icons that  oce sent me:

Check your work often at 100x100, don't just rely on guesswork as to what will or won't work at that size. I have a photoshop action set up that 'iconizes' files for me (duplicate image> flatten image > unsharp mask > image size 100x100) so I check them for their readability in every stage from sketch onward, sometimes a dozen times or more. I used to try to rely on guesswork, but it's very hit or miss - much better to be able to root out muddy or incomprehensible details early on in the process and fix them as you go!

The second is, consider the ratio of the size you're working at to 100x100. In my case, I like to use 500x500, so 5 pixels on the original will equate to 1 pixel on the final. This means that any line or detail thinner than around 5 pixels is not going to read well, so it gives you some sense of scale, and spares you from adding a bunch of small details that will just get lost completely when you make it smaller.

Hope that helps. :)

Personally i sketch it at 300x300, and check 100x100 often, line it and either shrink and color or do it before hand, seems to work a bit better than 500 pixels.

I tend to draw mine at 500x500 px, but zoomed WAY out. I'll usually view it at 25% or less while I'm working on it- when you zoom in it's way too easy to get overdetailed, and add things that won't read when iconized. It helps to work with big brushes and imply detail rather than putting it all in :3 and yes composition or nicely outlined shapes tend to help! That's my 2 cents :3