Revisions, Revisions

Other than surfing for MP3s last night, what I did mostly was revise old poems. I'm enjoying it, in some ways; in others, it creates a lot of anxiety, because I fear I don't know what I'm doing or if I'm improving anything. I guess I should just keep that Merwin poem "Berryman" to heart; no one knows if anything they're doing is good. I have trouble with the newer stuff; I guess I need time for the ideal version of the poem in my head to pass, so I can see how to improve the one on the page. Any tips for revision out there? I'm working on a book (for the next month) that's going to be critiqued at a writer's conference in June in Nebraska, so any tips would be appreciated.