If you set foot on land in most areas you are trespassing.
If wardens see you shooting birds that fall on private land (or in impoundments) you can be cited for wanton waste because you are not allowed to retrieve them.
That keeps most people out of creeks since hard to make them fall into public waters.
Suggest you observe locals and see how they hunt. Most will likely have marsh grass blinds that allow them to pull against the bank and hunt.
Decoy lines will need to be ready for tides or you will end up chasing decoys all day.
And please, please, do not set decoys in middle of creek or other areas that will obstruct boat traffic, you will lose decoys and probably get a good cussing from other hunters if you do.
Experience is much better teacher than websites- just saying.