Based on the questions you're asking, it's safe to assume you don't understand the contract form, negotiation process, values, repair costs, assignment form, state laws concerning practicing real estate, etc.

A more experienced investor can usually estimate repairs without consulting licensed technicians, but it takes practice.

Loopnet, Crexi, and building relationships with brokers are all good practice.

Lucie, it's also important to think about the practicalities of managing a vacation rental property.

And point 1st seems to be really difficult for me to put in practice, give the bad social relationship we 3 brothers have.

@Zachary Peacock And potentially more importantly, you can never be sued for practicing real estate without a license.

Triplexes within a half mile radius are being sold for practically double. 

Sounds like you're already doing this energetically (via voice)... just need to practice getting that into a different medium and laid out effectively. 

Spending enough time on training, roleplay and practice in the beginning is definitley critical.

Building and construction is a business, not merely  bunch of people practicing a trade.