What additional tips are there for keeping flour in good condition?

Since all cereal grains contain insect eggs, and flour is not heat-treated to kill them, unless flour is refrigerated (and even sometimes, then) or frozen, the eggs will ultimately hatch and flood the container with live larvae, moths, and webs.  Freezing flour for 48 hours prior to storage will kill any insect eggs in the flour.
 
If flour clumps (usually because it is absorbing moisture from the air) sift it into a shallow cake pan then allow it to dry out in a 200°F oven for a couple of hours. Cool before using or packaging in air-tight, vapor-proof packaging. 
 
If flour smells “off”, changes color, or becomes infested with insects, discard it. Buy flour in quantities that will be used in 2 or 3 months.

 
Source(s): 
extension.missouri.edu. “Using and Storing All-Purpose Flour.”