One of my approaches

One of my approaches is to code for and test the planned program's features one by one, so as to avoid plopping more code on top of a piece of code that's already bugged. (This is Proper Programming Procedure^TM, is it not?)

I also like to make my setups fairly modular: If I decide to change one important variable, or something else important to the program, the effect of the change will ripple through the program, meaning I won't have to manually change a bazillion things when I change the "big" setting.

Sometimes that means writing code later in the program that accounts for the values the "big variable" could be set to, not necessarily what the "big variable" is at the moment. With numbers, Python somewhat automatically changes the mathemetical calculation it will run, by plugging in different numbers. With word-usign variables that gets a bit trickier, and I may not have the time/energy for modularity in such cases.