I suppose you’d have to ask me after I’ve built something worth mentioning. At first sight, however, a lot of non-working boards discussed here seem to be due to lack of organisation. So I plan to knoll my components. See here for an example where I instinctively knolled a power supply kit before describing the parts on the mail day thread. As I’m colour blind I’d be a fool not to measure my resistances. This is especially important when for example you’re constructing a voltage divider.
Capacitances, I’d be inclined to trust the label, but I’d check polarity carefully and make sure I understand any annotations on the board and that they agree with the schematic.
Oh boy, transistor and IC pinouts. I’m actually paranoid enough to construct a simple test circuit on a breadboard just to make sure I’ve got it right.
Another step on from this would be arranging all the parts in order of construction. Maybe I’m careful enough to do that too.