Hi there John, It depends on what you want to accomplish/express... Try drawing or blowing and saying da,da,da or ka,ka,ka or ha,ha,ha or ta,ta,ta. You'll notice that each type gives you a different sound. Combining them : ta,da,ha or ha,da,ka will give you another effect. Extending one silible , taaaaaa,da,da will give you another result. Mixing them up, speeding them up will give you endless variations. Check out Jon's vids on youtube and if you think you've learned something, order his Rock n' Blues Harmonica Book and CD. It will help you with your questions and much more, it worked for me.... Perhaps you should also take a look at the Bending and Tone Workshop, downloadable from the main site.
Im having trouble with articulating,i understand that you have to do this to get the right sound from notes but i dont know when to, on what notes, and do you find 1 letter or word for all notes or what,i just dont get it. Some help would be appreciated.Thanks