First Thing's First
You gotta be able to make the noises. Spend some time just practicing with the sounds, and forget about stringing them together into beats. Some of the most basic sounds are:
--the thump, or synthetic bass drum
(Basically, just pronounce the word "boom" without parting your lips for the vowel)
--the gump, synthetic bass 2
(Who's coming up with these names? This is a pulsation in the throat, sort of like a short ribbit from a frog.)
--the K, synthesizing a snare
(Pronounce a K sound, and keep pushing air through your throat. This sound is nice because you can modify the way it sounds very greatly depending on how open your lips are.)
--the TS, or mouth hi hat
(Probably the simplest sound. Just say "ts".)
From here, you can handle most simple beatboxing. You can play around with how each sounds, and get a feel for what your mouth and throat are most inclined to do. For example, maybe you prefer to say "ssst" instead of "tsss" for a hi hat. You can play around with how long you keep the air flowing after a K, and so on.
Mastering the Beat
This part actually has absolutely nothing to do with beatboxing. This is a matter of rhythm. Before you can string the sounds together into a beautiful beat, you've got to have the timing down pat!! For this, practice with your hands or with drumsticks. Try counting 1-2-3-4 along with one of your favorite songs. (Most songs on the radio use this type of rhythm, though occasionally you'll get a different rhythm. Don't worry about those for right now.)
Once you can count along with ease, try making some rhythms on your own. 1-2-3-4-1-2-3-4-1-2-3-4-1-2-3-4 for at least a few minutes on end. Just try to follow something like bass-rest-snare-rest-bass-rest-snare-rest or bass-hi hat-snare-hi hat-bass-hi hat-snare-hi hat for now. You can designate your leg as bass and your stomach as hi hat and your shoulder as snare, or whatever you like. The point is to focus on keeping a regular time independent of a recording or a metronome.
Putting the Two Together
Now that you can produce the sounds vocally, and you know how to keep time well, you can start beatboxing. (Hooray!)
It's all going to come down to how well you can coordinate your tongue, throat, lips and breathing rate. As a general rule of thumb, you won't be able to breathe while you're making a sound. Therefore, you need to incorporate breathing into the beat. Whether it's breathing in or breathing out, you can use it as a substitute for a hi hat. To practice, this, try beatboxing a few bars using only your in breath and out breath. 1-2-3-4-1-2-3-4 where the odd numbers (1-2-3-4) are in and the even numbers (1-2-3-4) are out. Once you've got this down, you have got beatboxing down.
Playing Around
All that's left at this point is playing around with the sounds you make. Into your timed breathing exercises, try throwing in a K sound on the 3 (1-2-3-4) for a few bars. You'll find that you need to reorganize when you breathe in and when you breathe out. Eventually, you can try tossing in a thump or a gump on the 1 (1-2-3-4). (The gump is my personal preference.) You can start making up your own sounds and your own beat structures and all of that. Fun fun fun!!!
