These markets often offer attractive cap rates and stable rental demand.

Everyone is doing postcards, so you won't stand out, and regular folded letters just get tossed in the junk pile by default.Of course, this is all a moot point since you're operating in an incredibly specific (but high demand) niche.

Understanding how to uncover the potential opportunities by solving the seller/owners problem then engineering them to profit takes time & skill. 

@Aakshay Subramaniam First, you want to look for areas with high demand for rental properties and strong potential for appreciation.

Only the seller knows their true level of motivation to sell. 

Rarity isn't always the best thing especially if demand for this property type is low in your market.The reason I am bullish on adding ADUs is because I don't think the increased demand for ADUs is unique to New York.

Ask if they have "clear title", meaning has the title commitment/report come back from the title company with no issues for seller to fix/resolve. 

With inventory tight and demand high sellers don't have much reason to give a discount.

Their prices are reflective of the demand in the market and their backlog of work. 

That house was renovated (by seller, not me) and passed inspection (minor issues repaired) but until a house is stressed by daily living with  the occupant turning of faucets, heat/AC, opening windows, etc., a renovated older home will still have issues.