I second Michael's recommendation to check your safelight. Please consider using the Kodak test, and not a "coin test" or its variants. It will only take 10 minutes.
Originally Posted by Michael R 1974
Unsafe safelight that does not fog paper will reduce contrast and it will force you to use excessively hard contrast filtration, in addition to causing other issues with print-to-print consistency. Second to that would be checking your enlarger for significant light leaks.
I would say that 4 our 5 darkrooms which I have visited had unsafe safelights. All the other suggestions, which you got, are pretty good too.