This image is here because you don’t want to know what you get when you do a google image search for “tight.”
There are a lot of answers to this question but they all boil down to, “tight enough to keep air and water out, not tight enough to cause damage.” That simple answer may not be enough, though, because you have to consider the materials you are using.
Coaxial cables should be snug fit with a 7/16″ wrench about 1/4 turn beyond finger tight. Tightening them more than that can cause damage.
Lag bolts and other attachment points should be as tight as possible without driving into or splitting the material they are going into. This is going to really depend on what kind of wood or other material you’re driving the bolt into. In a case like this a good drill/driver with an adjustable clutch is a smart idea. Start with the clutch in the loosest position and then tighten it until you get a good, strong fit that doesn’t strip the bolt head or crack the wood.
Wing nuts and other attachment methods use for straps and chimney mounts should be very finger tight but no tighter. If you’re using a chimney mount you don’t want to put a lot of stress on the brick. Even though it “should” be capable of handling it, why take a chance?
Antennas or other items made of aluminum should only ever be finger tight. First of all, the metal will shrink and expand depending on the temperature so finger tight will give room for that. More importantly you will stress or tear the aluminum if you attempt to go tighter than that. Never use power tools to put together aluminum parts.
Home connection points that still use screws or twist-on connections should always be finger tight or just slightly less than finger tight. In cases like VGA connections the screws are there to make sure the connection doesn’t fall out, and even if the connector is partway in, it generally still has a good connection.
Push-on connections and connectors like USB, HDMI and Lightning should never be forced in. If it doesn’t go in nice and easy you’re not doing it right.
As I said, the real key is not having a specific number or amount of force in mind, it’s paying attention to the materials you’re using and making sure you’re never ever causing damage to the materials.