1) Obtain either Writers' Market or Jeff Herman's Guide. (Needn't be the latest edition, but shouldn't be more than three years old.)
2) Compile list of publishers which accept work like yours.
2a) Scratch out those that don't accept unagented submissions.
3) Cross-reference the remaining with P&E, Writer Beware, and AW.
3a) Scratch out any that are obviously suspect.
5) Confirm that the remaining publishers have books ON SHELVES in bookstores and/or libraries.
6) Begin the query process.