I don’t know how far along you are, but in the early days I think you’re supposed to appreciate Walter for how quick-thinking he is. And his sad lot in life is supposed to make him sympathetic, too.
He applies a little of his chemistry teaching to real life, has his former student sell the stuff. Make a little nest egg for the family. How complicated could it be?
Spoiler below in white text (needs to be highlighted to read as to protect those not through season 4.
poisons the boy