How to draw upon knowledge/problem solving skills when I need them, not when it's too late?

So many times I perform some task, and then some time later think "Oh shit I was supposed to do it this way instead" or "I forgot this step" or "What about this angle that I didn't consider".

I never act too hastily, I always think things through before I act. But no matter how hard I consider the situation, there are often things that I miss, and don't realize until later. It can be a matter of remembering details, or it can be an issue of problem solving/considering all avenues.

E.g. today I cooked, and an hour after I was finished, realized that I forgot to add this one ingredient at the very end of the recipe. Or last week I went to an office supply store to buy a cardboard box, because I'm selling an item on Ebay. It was only after I bought the box that I realized that given the price of the box, and how cheap the item is, I'd actually lose money trying to sell it.