Okay, first, most money hidden in walls is hidden in a place where you can reach in and get it - not boarded up and plastered over. People who hide money want to access it at their discretion, to add to it or take away from it as needed or circumstances dictate. SO, dont look for it to be blocked up, at least not at first.
Anything or any place you you can put your hands on and pull loose or access, like floor boards, bricks in fireplaces, window sill boards, cove molding boards, above door sills and shelves, etc., etc is a likely place for hidden caches.
In other words, from over head to just below your feet, is a likely range of possibilities. According to the "vision" youre working from, start with the walls - but dont stop there.
Think as if it was YOUR money you were stashing. Would you stash it so you couldnt get at it?
Now stand in the middle of each space you enter in the suspect house and ask yourself, "What places, seen and unseen, would make a good place to hide some money?
Iron ID features will be your best friend when hunting in a wall. They let you know what are nails and pipes and straps - and what are other metals. Everyone assumes Prince Albert tobacco tins were the only thing anyone ever hid money in, as if there was some secret "Money Hiders Container Code." Man, everything from folded newspaper to leather pouches, socks to jars, and yes tobacco tins has been used. I once found some coins in an old Zippo lighter shell... no lighter, just the shell full of coins.
So, since you dont want to tear a wall apart and either piss someone off or alert others to your searching - being able to discern one metal type from another is important.
Target separation, too, is critical, along with excellent pinpoint focus (manual GB would be a plus, but not absolutely needed in most houses.) Targets in a wall can be bunched together, and range in size from nail head size to tin can size - maybe even bigger. Consider what a bonus it would be to be able to ID, pinpoint AND get a good idea of target size with a few sweeps of the coil. Much of this is in the mind, while the right equipment allows your mind to work.
But, as a newcomer, you will need either extreme luck or plenty of skill with whatever detector you choose. Keep that in mind. Oh, and patience, plenty of patience. Me, I'd get a Tesoro Golden or Cibola, with the sniper coil. You do what you want.
Gool duck... You'll need it.
