This video I made explains it fairly well.
Remember that you don't drop your jaw for the /o/ sound. Also remember to roll your lips in and drop your jaw for the ɔ sound.
Here are some minimal pairs that might help you practice. These are DIFFERENT from the ones in the video.
I just made some meatballs, an American Italian treat. Now I have to make some red sauce to cook them in. Americans, especially in the Northeast, tend to call this "red gravy" or "red gravy food". I love red gravy food. But I know its not what you would eat in Italy. Its strictly American. But did you know that Italians often have difficulty with the difference between /i/ and /e/--the difference between bit and beat? So do Indians, Chinese, and often Russians/Eastern European and Polish people. I'll cover that in a future blog post.
Remember if you want to talk to me about taking ESL or accent reduction lessons, you can give me a call at (732) 807-5424 or you can reach me on Skype at david.berlin.esl (my Skype ID). Or you can check out my website at David Berlin's ESL and Accent Reduction Training or my American Idiom Of The Day Twitter Feed or my YouTube Channel . All right? All right. Look forward to hearing from you!