Most beginners puff from their lungs for each syllable or number. It is much better to use your tongue to break up the syllables and produce rhythm. Try whispering "Taa-Taa-Taa-Taa" through your harmonica into any hole.
Just use one gentle steady blow but break up its rhythm with a "taa" sound. Now vary your rhythm pattern much like the old Morse Code. Whisper, "Daa-dit-daa-dit-daa-dit".
Pronounce the words to a song while playing it on your harmonica. Think of it as "singing" through your instrument. It will improve your playing tremendously.
Oh Where Has My Little Dog Gone