A quick visual of the neighborhood will give you an idea of what to avoid, some are just streets of blighted properties.

And sounds like a good set of options you are looking at.Here's some data and visualization on recent trends in some of the markets mentioned here.

You've probably seen some of these before - basically, it's a visual representation of all of the materials that you'll be using for each room inside of the house.

We like postcards - they have higher visual impact and cost about 1/2 what letters cost, meaning we can hit twice as many people for the same marketing $.  

If they talk about relocating out of state, help them visualize what that we be like, with your help.

It's a little hard to have a clear idea without a better idea of the space, but I'd think a wall would be the least visually weird option.

@Roy Assaf ,All marketer marketing and hype aside.....1 Absolutely agree with @Michael Quarles  that yellows are the wrong approach for multifam....especially in Brooklyn. 2 Sample size is small, but to get ZERO calls, not even a "go to hell" or "I'm gonna shoot you in the head"....there's definitely something wrong.I assume you've checked all the basics, actually visually inspected your RTS to make sure everything is printed properly and phone number legible?

You will probably hear more than you could possibly find out by visual inspection from things like what’s buried in the backyard to the fence being propped up by sticks.4.

The thing is, a printer-applied address is a dead give-away that yours is a direct mail piece because the print lays flat on the paper, unlike when you hand-write an address, which gives visual texture.I think too much is made of using yellow legal pad paper. 

ciao Hey  April, 1. all of my free professional time is spent researching, working, educating myself on REI. about 20-25 hours. 2. we are using a handwritten style note on white paper with some kind of corporate branding , check out openlettermarketing .com. for visual examples.