For starters, I'd study how the ramrod is sitting in its holder under the barrel. The tip of the ramrod should be about even with the muzzle. Next take the ramrod and drop it down the barrel. If it's now sticking out way past the muzzle it's a good chance that the gun is loaded. If it looks like it's about the same as when it was in the holder, it should be unloaded.
Shine a light down there too. If there's a ball and patch down there, you should see it.
I would then run some patches down the barrel with a cleaner, I like good old windex myself. Clean and dry the barrel. Next I would remove the nipple. Clean that, then add some breech plug grease to the threads and reinstall.
Load er up and shoot.
Keeping your gun clean is probably the most important part of muzzleloading.