If you are having trouble extorting business owners, try destroying some of 
their property and/or
hold a gun to their face. For example, when you are trying to take over Good 
Eats in Brooklyn,
you can hold a gun to the man's face then reholster the gun and extort. If 
he refuses, simply draw
your gun again, lock on, and hold it. Keep doing this until he caves in. Do 
not forget to reholster
your gun to avoid accidentally shooting him. In another example, when you 
are trying to extort
money from the hotel owner in Brooklyn, hold a gun to him twice, break the 
downstairs cupboard,
then finally blow his safe before you beat him into submission. Always buy 
available rackets first.
Take a trip around to either buy another racket or go around the block. Do 
not attack until you
visit again, and instead of enemy soldiers you will find all your soldiers. 
By doing this you do not
have to fight a bunch of enemies and get your vendetta up. If you have not 
taken over all the
businesses and rackets, wait until you have reached the "Don Of New York 
City" rank. You
will be able to take over anything without having to smash anything up or 
"convince" the person
that it is a good idea; they will just say "Yes" immediately.