My keys to public land success:
1) SCOUT scout and scout some more. Scout months before, week before, day before and all times in between. Be smarter than the Yahoo's.
2). As mentioned, a simple relaxed spread ideally exactly mimicking what you observed while scouting as far as species and numbers and activity. Special decoys like sleepers, feeders, etc. or alternative species would help in making the spread look different from everyone else.
3) Calling: Very very easy on the mallard call, few quacks, maybe a comeback call. Instead, buy a 6-in-1 whistle and learn to use the heck out of it as needed. Teal peeps, widgeon sounds, mallard drakes, pintail whistling, etc. Learn them all, depending on what species are prevalent in your area. No loud hail calls on the mallard call. (that's what all the yahoo's are doing)
4). Don't tell people of your successes, be discrete and enjoy it!!! Don't post pics and reports on local websites, etc.
05-06 Season 141 ducks in 8 hunts, all on various public land tracts.