I thought I'd repost this in the Tutorials form. The original WIP I developed it for is here: The Union of Holy Kingdoms
This tutorial was done in/for CS2, but it's probably adaptable to later editions of CS, and maybe even Gimp for all I know.
1. I start off with a basic shield shape, ideally large enough to handle any artwork, but not so large that when you shrink it down to place on your map, the details lose all definition. My black shield is about 500 pixels in size. You can find shield templates free for private use all over the web; I drew mine, but just do a google search if you don't feel like making your own. Create a brush from it in PS.
2. Once you have your base shield, open a new PS document: 700x700, 300 resolution, RGB color/8 bit. Make the Background layer Invisible, so that when you eventually save your coat-of-arms design, you don't have a white box around it.
3. Create a new layer, name it 'base shield'.
4. Select the brush tool and find your shield brush that you just created it. Put in one shield in the approximate center of the document.
5. Duplicate the 'base shield' layer. Rename it 'rim'.
6. Make the 'base shield' layer invisible, then (you should still be on the 'rim' layer) click Select-->Color Range-->click the black area of the rim layer-->set Fuzziness to 200 -->hit OK. Then, Select-->Modify--> Contract-->5 pixels--> hit OK. Hit Delete, then Deselect.
7. What you should see is basically a 5 pixel wide outline of your base shield shape. Now you're going to add some color and definition to this shield rim by adding a couple of layer styles. So hit Layer-->Layer Style--> Color Overlay. I went with hex #:c7bd25, set at 100% opacity.
8. Now we add a bevel to the rim. Layer--> Layer Style--> Bevel & Emboss--> leave everything at the default setting. Then click Contour, and change the shape to a Half-Round.
**At this point, Save your file as something like 'Shield Template'.**
9. Now that your shield's outer rim is done, click back on the 'base shield' layer and make the layer visible again. This is where your design sense (or lack of it) comes into play, because from here on in, it's all imagination. What I usually do to start out creating a coat of arms is to have a design already sort-of visualized in my mind's eye. Let's do a simple one - I want to do a coat of arms with a golden dragon on a field that's split in half, the left half green, the right half red.
10. Start out by adding a layer style of Color Overlay to your 'base shield' layer. Since I know I want half the shield's field to be red, I'll just leave the color overlay at a suitable red, #e12d24.
11. Create a new layer; name it 'color box'. This layer should be between the 'rim' layer and the 'base shield' layer. Click the Rectangular Marqee tool in your toolbar. Starting from a point above and to the left of your shield, click and drag out a box. Try to get the right side of the box as close to the centerline of the shield as you can. Now, with that marquee box still active, click on the foreground color of your two color boxes in the toolbar. Choose the green color you want the other half of your shield to be. I chose #15894f. Then click Edit-->Fill-->Foreground Color (from the dropdown box on the menu that comes up). This fills your selection box with green. Deselect.
***Note: You can also add multiple, different layers to represent different shapes, etc., from a quartered field, diagonals, checkerboards, etc.***
12. Control+Click on the 'base shield' layer, then Select-->Inverse-->Delete. This removes the bits of green outside the shield.
13. Click on the 'rim' layer. Now, there's a couple of ways you can go here. If you trust your artistic ability enough, at this point you can create a new layer, name it 'dragon', and draw in your own dragon (first making sure you've set your foreground color to the color you want the dragon to be). If you want to save time, or can't draw, you'll need your friend and mine, clipart! There are literally hundreds of thousands of heraldric images around the web, many of which are free for private use. Once you find a suitable dragon, save it to your computer. Then follow steps 13a - 13e. If you've drawn your own dragon, continue on to step 14.
13a. This step involves adding predrawn images, as opposed to drawing your own. Make sure you're on the 'rim' layer, then File-->Place-->select the clipart dragon image you found. The image will probably be much much larger than you want it to be, but that's okay. Click on the Magnification tool. You'll get a prompt that asks if you want to place the image; click Yes. Now you've got a big dragon that probably takes up the whole screen. I tend to use easily-editable images, because A) the less line-work there is, the less editing you'll have to do, and B) when you shrink the end-product down, you don't end up with a blurry mess. I also use only black and white images, because it's easier to add color when you're starting from a B&W base.
13b. Right click on the dragon layer and select Rasterize.
13c. You probably have a large white box around your dragon at this point. To get rid of all the white, just leaving the black dragon, Select-->Color Range--> click in the white area. Select a Fuzziness of 200, then hit OK. Delete. Now you're left with just the black dragon shape. It's probably overlapping your shield rim, but we'll fix that a bit later.
13d. Now I want to make my black dragon a gold color instead. First, make every layer below the dragon invisible. This is so that when you select the areas to change color, you don't change anything on the other layers. Next, Select-->Color Range--> click somewhere in the black dragon. Then choose your foreground color; I went with #e5ec1c. Edit-->Fill--> Foreground Color (the gold color you just did)-->OK. Then Deselect. Now make all the other layers (except Background) visible again.
13e. Now I want to resize the dragon to fit on the shield where I want it. Edit-->Free Transform. This creates a box around the dragon image which you can then use to manipulate the size and orientation. For something simple like this, just go to the top of the screen, where you'll see some options like X, Y, W, H. W & H are the ones we're going to use - they're Width and Height. Play around with entering different values until you find some dimensions for your dragon you like. When you're happy, click on the Magnifying tool. You'll see a pop-up that says 'Apply Transformation?' Hit Apply. Now, move the 'dragon' layer beneath the 'rim' layer.
14. This is useable as-is, if you want it to be, but I like to add some shadows and hightlights. So, click on the 'rim' layer, then Shift+Click on the 'base shield' layer. Four layers should be highlighted, from top to bottom: rim, dragon, color box, base shield. Now merge those layers.
15. Now we're going to apply a layer style of bevel & emboss to the whole thing, so go to Layer-->Layer Style--> Bevel & Emboss. I use these settings, but you can certainly play around and find something that appeals more to you.
Highlight Opacity: 30
Everything Else: default.
16. Then click Contour and change the shape to Half Round. Then hit OK.
17. This is now done. I usually save as a PNG file so I don't get any JPEG pixellization. I attached two pictures below; the right hand one uses the Bevel/Emboss values from above, while the one on the left uses the default Highlight value.
18. To start a new shield design, Edit--> Step Backwards twice. This removes the Bevel/Emboss, and breaks out the layers again. Now you can delete the 'dragon' and 'color box' layers and start over again.
IMPORTANT: MAKE SURE YOU SAVED A BASE FILE TO RE-USE FOR NEW COATS OF ARMS AS DESCRIBED IN STEP 8.
Now that you have a completed coat of arms, you can place it on your map. On my UHK map, I scaled them down to 30%, 50%, or 75% (the side-bar shields), using the Free Transform function.
Hopefully this has been a bit of help!