I - many long-distance supply chains are unreliable or broken
II - long-distance supply chains are broken, even for essential bulk goods
III - local social collapse / [civil] war zone
Which might be summarized as (I) stockpile tech stuff, (II) stockpile food & fuel, and (III) join a hard-core local militia
In general, though, I'd assume that electricity would be highly constrained. So I'd focus on very low-power or no-power tech and components.
In terms of information, I'd prefer it in dead-tree form over electronic.
Backup wikipedia, openstreetmap, survival informational handbooks, and lots of fiction reading entertainment.