Different ways to get a dragon:
1. Find a dragon, different dragons have different preferred biomes, tame said dragon with either raw or cooked pork. This could be dangerous since the dragon could very well kill you.
2. Find a dragon nest, a spawner of sorts, and steal an egg. Hatch egg in furnace or perhaps an open fire (a block of wood on fire).
Congratulations you now have a dragon you can ride! New!
1. Constant companion mechanism - The dragon will fallow and protect you if you choose not to ride him/her. The likelihood of this happening is raised when you hatch the dragon rather than tame it. To keep the dragon from fallowing you, perhaps you can do as the "You are Creeper" mod does and give it a red or yellow flower, this would be useful if you don't want it to crash through your house or mining tunnel.
2. Fire power- Long rang weaponry based on your dragons element. So while your flying you can burn/freeze/crush/etc mobs. To add to the difficulty, the dragon could have it's own health points that you can see under your own and of course you can heal it like you do yourself, with food. Hmm, it might be to this mods benefit to have more food added in, like a steak drop from cows and lamb chop drop from sheep. Hell maybe even rotted meat from zombies.
Fangs/claws for arrow or spear tips, bones, sulfur, and a tougher sort of hide for armor. Perhaps even an egg.
Dependent on biomes. So a colder biome would have dragons who maybe thicker and lighter in color. Warmer could be the opposite. Though you could get a dragon that lives near or in a lave pit, so their coloration maybe red, orange, or yellow. But you get the idea.
Saddles would also need to be integrated into this mod. Also perhaps the ability to create nests, dragon spawners, could be added, this could allow, if your dragon gets killed by accident, for the dragon to respawn. Oh, maybe the dragon could even automatically go back to it's respawn point and allow for quick travel.
That's it for now I'll have, I'll add more if I come up with something else.
Well this sorta ties in with my Dragon Mod. Perhaps I could make a side mod for this, after i finish Dragon Mod?
Ah, see I didn't know about your mod. It doesn't help that the search feature is off. But yeah, you can use these ideas in your mod so it's more than just a new mob. :3 Or someone else can create this mod separate from yours.