If you are thinking of checking out best Black Friday TV deals this year for an upgrade to your existing TV set there are two big questions you need to consider: how much of a difference will you really notice; and how much do you need to spend to see a difference that is really worth having?

The answers to these questions depend on the age, size and screen technology of your old TV. I can’t possibly cover every model here, so I’ll offer a crash course on what you can generally expect in terms of upgrades, depending on what year you last bought a TV, and tell you which new models to look out for it will deliver what you are looking for.