I've been playing Godfather Blackhand Edition now for a couple of days since it was released here in the UK and here's some tips that I'd like to share with you.
When you first try and extort a shopkeeper a bar will appear underneath his health which shows you the point where you've pushed him too far. You can keep roughing him up until just before this point. The more you rough him up the more money you will get from him. Try doing a few things to get his weak spot - some shopkeepers hate for their shop to be broken up, some hate to be thrown about, some hate to be hit, and some hate to have their customers beaten up. Do a bit of each and you'll quickly get to know his weak spot. Just make sure you dont kill anyone - especially the shopkeeper.
If you try and extort a shopkeeper while a rival family is stood outside then be sure to get into a fight. They dont like anyone muscling in on their shopkeepers and they'll come at with full force so take these guys out first.
Getting Rid of Rival Family Mob Members
For this its always best to have cops in the local vicinity on your side. Bribe about 4 cops (costs $250 each to begin with) and make your way to the shop (make sure your gun is hidden). Go down the side alley next to the shop and you will see a rival mob family member guarding the back door. Choke him to death, beat him to death or garrote him (this gives between 300 and 400 respect points). Killing one guy becomes more difficult if there are 2 guys down the alley - choke one half to death and then beat the other guy up. It may be possible to get an execution hit on one guy while he's half dead. Learn these as they become a fast way of killing people. If there is a burning oil drum nearby then use it. Grab him and throw him over to the burning oil drum. Teach a man to make a fire and he will be warm for a few hours - set a man on fire and he will be warm for the rest of his life
With the alley guards dead walk up to the street and pin yourself against the wall, get your gun out and Z-target a mob guy thats stood just around the corner on the street. Target the head and take one shot. Most of the time you will get off a clean shot and he's down. The other guys come running but the sound of the gun will also bring cops running and being as they are on the payroll they will start shooting at the rival mob family and not you. If no cops are nearby then just Z-target a rival member and shoot. The wall will provide the cover you need. Shoot at the rival members to kill them, strangle them to death or just wait until the cops do your dirty work. The rival members may drop health packs so strangling them to death or beating them up will always get you more respect points. A kill via a gun will always get you low points (between 20 and 100) but using your fists will earn you more respect.
Buying out rackets
Once the rival members are dead you can hang around and mourn the dead or enter the shop to extort the shopkeeper. Once the shopkeeper is on your side the door to the back will become unlocked. This leads to the racket behind the shop if there is one. If you walk up to a rival mob family member with your gun out, they will shoot at you. If you hide your gun and as long as things are peaceful between your family and theirs then you should be able to walk around the rooms without getting shot at. Sometimes, however, they will shoot at you without first asking questions. Either kill all mob members as you walk through the rooms or just walk straight past them and find the guy who controls the racket and buy him out. If a rival mob member is on his own then kill him with your bare hands. Never have your gun out when walking into an area. Have it ready to bring out and shoot if need be but if they dont shoot at you then its much easier to walk around.
With most rackets there is a safe. Bring along some dynamite and blow that safe open. Always make sure that the guy who runs the racket is nowhere near the safe cos if he dies then you will lose money on the racket. Grab him and move him to the opposite end of the room behind crates if there are any before planting the dynamite. You have 5 seconds after planting it to get clear.
Its always best to have a few safe houses that you can go to when in times of trouble. There is one just to the west of your starting safehouse that was owned by the Tattaglia family which cost $15,000 (make sure you have enough). Take out the rival mob members and buy the safehouse. Buying this safe house gave me a room full of guns so I always make sure I have enough firepower when going out.
Thats enough for now. Please do add your own tips as well...