Game is great Doing campaign was a bit boring imo, but since then playing has become more meaningful. Get a few friends to play it or just solo grind, both are fine. Test all heros to 1 - 70/80 at least and be open mind about skill, test all of them. Pick one build to each hero and grind decent gear for them.

But if you want some hints and tips then here are few videos :

https://m.youtube.com/watch?v=tBHg7A13x94

https://m.youtube.com/watch?v=X8IBK9cd60M

https://m.youtube.com/watch?v=IhCwxTGUvbI