Whenever I've started something new, I've shown great excitement in coming up with what seemed like interesting ideas to me, only to be told that the ideas have all been tried already and resulted in failure. It usually takes tens of ideas before I come up with even one that hasn't been tried before.

But the objective is not always to come up with something that hasn't been tried before. As that can be incredibly hard.

The quickest way to gain deeper knowledge in a domain is to come up with ideas in that domain and then try to understand why they failed (if they have failed before).

As you do this, you will soon start coming up with ideas from a deeper level of understanding, and with an increasing probability that they haven't already been tried before and resulted in failure.

There is no substitute for experience.

However, how quickly you gain that experience is up to you.

Start coming up with ideas. And follow up on them.