Balance---- I just mean leaving a small balance in the account. I don't think the amount is important (just my opinion). But only sending money directly through would appear to be a large red flag. Especially with no other history
or sending A-->B and B-->A (terrible idea).

Not necessarily making a purchase with the same card, only from the same account. Using amazon to make a purchase every once in a while should def. help with the account history. I have used my amazon account for years for purchases; so losing my account and/or relationship with them is not something I wish to endure.

However, you should note, I am very new to AP, but not to amazon.
I am not an educated CC churner here (mostly have been around the hotel, airlines, and car rental threads). Considering those options, but for now, just make an addition to earn a few more miles/ points.

Also, from all the detailed info. here, on blogs, and the AP T&C, leads me to an educated opinion.

I think using various methods would be much better than taking the lazy route and exploiting one system.^ I think it takes time to read and educate yourself, and then carefully plan and follow through to be successful long-term. (again, this is just my opinion).