I am enjoying writing dialogue for my new play that is set in an immigration office. I used to work in immigration so I have many experiences to draw upon. Apparently I have a problem shifting tenses in my play and the converted short stories from the play. I'm not sure where to learn more about my grammar issues. I have taken grammar quizzes on-line and studied from books, but I have a long way to go. In school I could always count on what sounded right and I never learned the nuts and bolts.
I have place my writing on critique sights and I get a lot of help there and from friends and family that proofread, but I need to learn. Any suggestions?