Find a firearm that's been sitting unused for a while. Inspect it for any signs of neglect (rust, corrosion, dust). What condition is it in, and what does it need?
Take one firearm completely apart (field strip or full strip, depending on your comfort level). Document the process with photos or a quick video. What did you learn about how it's built?
Grab your current lubricant and tell us: What are you using, why did you choose it, and have you ever tried anything different? If you're willing, compare it to another option and report back.
Do you maintain different calibers the same way, or do you adjust your routine? Pick two firearms in different calibers and walk us through how your maintenance differs (if at all). What's the reasoning?