Whenever you are making a recording of an individual (this does not include video with no audio in a public place) usually at least one party to the conversation needs to be aware of the recording. In other words, you cannot put a device to record all phone calls on a line, unless you are always a party to those phone calls. Also, you cannot "accidentally" leave a recording device in another room and walk out to record what took place in the other room. Exceptions to this require a judges order.
In other words, you cannot bug anyone's car, apartment, house, office... you name it.
You can, in one party state (meaning one party to the conversation is aware) walk around and record everything without telling anyone. You can use a hidden camera and record everything that is going on around you (there are some facilities that can outlaw this).
Some states require both parties to be aware they are being recorded. These states are:
Assume places like Washington D.C. and other US places to be 2 party unless you can find something to clearly state otherwise.
This means in 2 party states you cannot secretly record any conversation or use a hidden camera with audio. You can use a hidden camera without audio in public places.
Whatever you do - Stay safe!