Looking at a 8-unit in NY for a first deal, need advice.

[Collwyn Cleveland]

There's a 8 unit building here in my hometown of Brooklyn, NY. The owner is elderly and has intimated to a few folks that she might be willing to sell the building if the buyers approach her properly (lawyers and such).

It's vacant due to a structural concern vacate order by the city, so it needs repair. It's not officially on the market.
I sent the owner a letter introducing myself and my interest in the building.  I've never done anything like this before, but I may have a potential investor but I need to get my work done beforehand. What should my next step be?