I tend to work interior monologue into the other paragraphs rather than quarantining it off in its own.

Example:

God, 7:10? Late, and on school picture day, too. I set a record for fastest shower, but skidded to a stop in front of the mirror. Part of my hair was dark and stiff, the exact color my sister had been painting her stupid diorama. With oil-based enamel paint Dad said she could use.

Great. Not only would my painted head be captured for all time in the yearbook, but Chris Townsend would see it first period, and third. I might as well just slash my wrists now.

Me again. That works the narrator’s (your) thoughts, the interior monologue, into every paragraph. Not that my silly example was good, but I hope it illustrates the method.