I'm definitely gonna have to agree with AK on this one...you just need a little bit more conviction in your voice and you have to keep control during transition from phrase to phrase. Command is a must. Practice will make it better....Try flowing to all types of beats or sometimes just freestyling without an instrumental...Another thing that might work better if u feel like you are more comfortable freestyling than spitting off paper...just get an image in ur head and try to focus on letting it transition...you spit as the scene change....That will teach concentration as well as rhythm. Once you get the rhythm down then you can spit off paper.