I'm speaking from a bodhran perspective, but it works perfectly well for me when I play bouzouki.

done mnemonically if you play every beat you get

jel-ly-and, ice-cream-and, choc'-lat-sauce. DUD,UDU,DUD

now you can either start your next bar with an U or if you can do a fast double on the last beat of the bar before then you can always start on an upbeat .

If you want to leave beats out (ie not play all 9 in a bar) you leave out the middle one in any group of three.

change of food

ba-con-&, eggs &, saus-ag-es = DUD, U-D, UDU (leaves out beat 5)

just swap the food to leave out different beats

eggs- &, ba-con-&, saus-ag-es = D-U, DUD, UDU (leaves out beat 2)

saus-ag-es, ba-con-&, eggs- &, = DUD, UDU,D-U (leaves out beat 8)

hope that helps

slainte

alison