Write all your freestyles, or record, then brush them up, memorize those lines that your like 'wow, did I say that?' And but them to the back of your brain, then in your bedroom, rap about your chair, then your bed, then the wardrobe, etc. (again record these), once you've listened to them, I've always been told to add metaphors, so always include one or two a verse. Then start battling the big boys (Y), when you feel your ready that is. Good luck.