Do you know why 95% of the traders fail? There could be a myriad of reasons, but my own opinion is that they don't "specialize" until they become really good at it. This is especially true when it comes to futures. I encourage you to stick to 1 instrument until you can read its price behavior like the back of your hand. This can take years. But it will be well worth it in the end.
But don't many instruments move in tandem with the larger economy?
You're never gonna see the Dow drop 10% and the Nasdaq do nothing.