Aren't most of the hacks and their features Patched with today's patch? ._.'
There are many things you can do.
If the Hack contains a D3D Menu (A live menu in the game) you should:
Install Microsoft .NET Framework 4: Here
Install DirectX 9: Here
Install Visual C++ Redistributable: Here
If you don't have any installed.
You should also check your FireWall and Anti-Virus, they should maybe be disabled so you can use some hacks and injectors.
If you are using Windows 7 or Vista you NEED to execute your Injector as Admin.
The Hack CAN be Patched, so it'll not work in-game.