I'm getting better at not forgetting debt, but I'm not all the way there.
If you're only playing a small number of actions each turn—or rather, drawing cards a small number of times—putting your debt tokens on top of your draw pile is sure to remind you during the clean-up phase (when you draw). It's usually pretty easy to recover the right game state by then, which most often is right before your first buy. (Probably the beginning of the buy phase works too since no one got any extra information, edge case Venture.)
If you draw cards many times, shuffling the debt tokens back and forth becomes cumbersome. In your buy phase, putting all of your treasures, virtual money and debt tokens in one spread-out pile lets you easily see how much money you have; making that a habit will likely make you forget your debt less often.
Usually I place my terminals (including Throne trees) on top of my villages for tracking purposes, so rearranging your terminal virtual money is only recommended in games where the number of actions you have doesn't matter once you get to your buy phase. (Anti-synergies: Villa and, less so, Diadem.)