being thousand km apart, strategies may be different according to field,no of ducks,weather etc etc.
but i had same problem like yours until this season....those God damn pinnies will just circle out of range two or three times,show no interest in decoys and just turn away. i was using 6 pintail decoys at those times mixed with mallards.my little experience shows that they dont land with mallards most of the time.i havent seen them even once !
this year i added up 6 more magnums and started making a spread with 12-16 mallard decoys on one side and 12 pintails (6 standard/6 magnums) with 12 to 20 teals mixed on other side of the blind.....and guess what, birds started landing right in front of me over teal/pintail spread. not a single bird landed in mallard area. we shot a dozen on first day and about 8 or 9 on second shoot. as spread was near my blind (max 20 yards radius) so i switched to no#8 for early 15 to 20 minutes and birds were dropping stone dead!
one more thing which is must is to buy a pintail whistle and know how to operate it.
good luck for your first pinny,i hope u get more than one.