I used to think that Breakfree cleaner/lubricant was standard issue in the military because some general's brother-in-law was a salesman for the company. But tests have subsequently shown Breakfree CLP to be an excellent metal protectant. When I finish cleaning a muzzleloader barrel, I run a dry patch, then a patch saturated with Breakfree CLP. I can then store the gun with confidence.
A swipe with Breakfree around the very lightly fouled areas (such as the trigger group) is also a good idea. Do not, however, use WD-40. While it may be among the best squeak stoppers and penetrants, it is a very poor lubricant or protectant, with low film strength.
Bore Cleaners
For bore cleaning, commercial black powder cleaners are fine, but they aren't always readily available, particularly while traveling. But you can generally find Windex glass cleaner anywhere. And the ammonia-based cleaner is very effective even on copper fouling.
Stay away from animal-based concoctions. It is silly to think that a modern steel barrel can be seasoned like a cast iron skillet. Granted, some early animal-based lubricants were great such as sperm whale oil. But you are not going to find it readily available and the modern alternatives are better anyhow.
Breech Plug Lubricants Vary
There are plenty of specifically designed breech plug cleaners and lubricants available commercially, but there are others outside the normal muzzleloading brand names that work just as well, if not better.
What you need is a high-temperature grease that works for the fraction of a second that the breech plug sees direct heat. Try common automotive Anti-Seize products that meet Mil-Spec 907E, such as Bostik Never-Seez, and you're good.
Breechplugs vary, of course, by manufacturer, but just to be sure to coat all the threads and you'll be fine.
Hodgdon Triple Seven has long been a personal favorite propellant, but I've heard more than few complaints about it causing problems with breech plug fouling.
To avoid that problem, take time to crack and then retighten the breechplug after a few shots at the range. This will break the bond line that can form, and makes removal at the end of the day much, much simpler.
In fact, this sequence helps in almost all inline rifles, regardless of propellant.