BoP Medals

Medals live in the Frontres directory. There is a big bitmap (286 * 288 / 256 colour) for the main plaque and (however many missions you have) little 256 colour bitmaps for the "jewels". Each time you look at the medal in the game it displays the big bitmap and then overprints it with the little ones according to how far you have got in the campaign. I would suggest that you use nice descriptive names for them.
For the big bitmap choose a nice simple design to make it easier to plan where the "jewels" will appear. Use your judgement on what to make it look like but I would suggest a shield, or a plate, or a plaque, or maybe a starmap with the jewels slotting in to represent conquered systems.
Since the game seems to only add "jewels" for the last 15 this is the maximum you should plan for, and it also means that if you have 15 missions or more that if you like you can simply edit the "normal" plaque to have your design in the centre.

For the little bitmaps you can either repeat the same little design, or if you want the work use a different design for each. There are three methods possible:
Firstly if you have chosen to use a modified version of the "normal" plaque as your main medal you can simply edit the "normal" jewels, either drawing over them, changing their colour balance (if that is what you did to the plaque, you can get some nice effects so it looks like a different metal), or blacking out the "metal" surrounding the actual "jewel".
Second if you are using a new plaque you can draw your "jewel" and then adjust the size of the picture so that the "jewel" is at the same co-ordinates in the little picture as it should be on the plaque. This could be tricky to get right though (I haven't tried it).
Thirdly if you have a paint package that supports layers then you could draw (or import) your "jewel" and then position it by eye, reduce the layer with the plaque to 0% visibility, and then crop and save the required area. I have unfortunately found in my experimentation's that a nearly black outline appears around the "jewel" which seems to be a result of reducing the colour depth back down to 256. You may have to either go around the "jewel" with true black colour or use the layers option to only produce guide-points and then paste a copy of your "jewel" over the top.

There are two list files to edit to make the game use your bitmaps.
The first is Campawds.lst which has a list of the bitmaps to be used as Campaign Awards. It has a definition of its format at the top. Change the number of Campaigns, put in a comment for the name of your campaign, its number, and names for the big medal and the little "jewels" (not the filename though probably similar).
The second is Top.lst, which you may or may not have been into before. Here is where you define what the names you have added to Campawds.lst for the bitmaps actually mean. Add lines showing the filename, the name you have chosen, and then 1 (I do not know what the "1" defines but it is used for all the Rebel and Imperial lines defining their medals).