How can i learn to articulate my words more?

it's so difficult for me to do this sometimes. what should i do? i can write amazingly, making me sound as though i really know how to express myself, but when it actually comes to me speaking i sometimes have trouble. is it b/c i am a minority or something? i don't speak in a ghetto manner, in fact i sound "white" as many people put it. but, what could be the issue?