I don't know how effective this'll be as a tutorial, but hopefully it'll give you some ideas, and maybe show you some tricks you haven't thought of. I was going to write in the picture itself, but in the interest of being kind on slower connections, I've shrunk the image to 1/4 the original size, and just slapped number on the frames. So here we go!

Step:
1. If your doing a keychain, or something similar. It's a good idea to have a referance. In this case I used the referance to get a rough idea of how her head would look on a 3D plane, then tilted it around to the angle I wanted.
Also worth pointing out, I'm working with Fimo here, on a Bawls advertisement.
The reason for this is you have to bake Fimo to finalize that piece. When working with a "flat" piece like this, the fimo sticks to what you're working on. By preparing for that, you can actually use that fact to your advantage by making whatever it sticks to, large enough for you to work with, but small enough to easily plop into the oven.

2. Select your tools. Or at least most've em. In this paticular instance, I only used the one dental tool (with a blunted tip) to sculpt/cut/smooth with. I'd planned on using the Stanley knife to cut away excess, but it was too unweildy. Instead I would carefully poke tons of holes into the excess and pull it away. (look at the botom right to see what I mean)

3. Small concession here, I forgot to take photos constantly. Basically all I did here was squish the ball flat onto the Bawls placard. Shaping it loosely to what I was after. Using the dental tool I did a very light trace of how I thought the ears should look. Then I cut away the excess. This paticular dental tool is shaped like an L with a slight dip in the bottom of the L. I made the best of that by pressing it backwards into the ear so that the tips would only be slightly sunken whilst the botom of the ear would look appropriatly deep.
Realising I'd need a hook hole, I cut some of my sewing string off and dug a trench into the head for the string to fit into.

4. String in place, I realised that it'd be better to have a more solid hook hole. Softening up the excess I'd cut off eairlier, I shoved the string into it and put it in place.
In hindsight, I should've rolled the hook fimo out and fed it into the trench. This would've further insured it'd be firmly in place. Looking on the back of the finished piece though, it sealed up fine anywho, so it shouldn't break off.
You should note that little detail for your own piece though. If you're adding something in, try to make trenches or holes for the new material to grab onto. If it's perfectly smooth. You run the risk of something just resting on top of the main part. Which could result in a chunk breaking off along this weak spot.

5. Using the side of the dental tool, I raked the fimo back over and smoothed it to lock the string in place. Again, if this've been the fimo from the hook, it would've welded the piece even tighter.

6. With a more solid plan, I begin to dig into the fimo, making more distinguished 3D shapes to build on. Which is when I spot a flaw. The head is too flat.

7. Toutching back on what I said before. I punch holes into where I plan to put some fimo. I also roll the new fimo in my hand extremely fast, trying to get it as hot (pliable) as possible before I put it on.

8. Twack! I was "careful" here, using the dental tool and my finger to try and coax the fimo into the holes, whilst trying to avoid smushing other details or flattening too much.

9. With the shapes about where I wanted them, I scraped lightly along the fimo to try and give the impression of fur. Making sure to both A. trace her marking outlines first. As well as B. pulling the tool in the direction the fur should be going. Just on the off chance it'd dig in too deepily, I wanted to have it suggest the direction of the fur rather than just be a mistake.

10. Time to add her name! This was one of those forehead slap moments. Normally I shove some excess off to the side but keep it connected to the main piece, that way when it comes time to make the letters, I don't have to worry about the seal. Oooooh well!

11. as I was working, I remembered that I'd seen Delilah wearing a bell collar the once. Thinking this'd be a neat detail, I decided to make the name a little more involved. Shaping it so that it looked like she was wearing a collar on her neck. As I dot traced the letters (Dragging the dental tool becomes a no-no after you've laid down that much detail) I worked the colar in further. Turning the bell into the dot on the I. Something the dental tool was not up for at this scale I might add. Instead I used a razor tip scalpel, wiggling just slightly to make the hole tips in the bell. (two holes can be seen on the bell)
Content with the overall shape once again. I gave myself a lil pat on the back, and began dot-cutting the letters. Occasionally using the bottom of the tool to press the material down and help make the letters stand out further. I also had an incident involving the D where I pressed too hard and poked all the way through. While it -looks- nice. It makes a structural weakpoint on the piece. A bit of fimo tucked into the hole (and sealed in) and it was good as new!

So there you are folks. I hope this has helped give you some ideas. Maybe shown you a few things to do, and a few to avoid.
Oh, and some final tips for working with fimo. When it comes time to paint it. Be sure to;
1. wash it with alchohol to degrease the fimo. Otherwise your paint won't work as well.
2. AVOID any petrolium based products. (Enamels and Paints that can be cleaned up with paint thinner typically fall into this category) The reason for this is that petorlium will corrode your fimo, causing it to break down in months rather than years.
3. AVOID Spray paint cans for the same reason.
4. If you use watercolors or paints like those. Be sure to cover the piece with a (non petrolium) sealer to lock the colors in. Otherwise you might have to constantly toutch it up as the colors bleed off.