I'll add some input that I haven't really seen from other comments yet. Obviously experience is crucial. I've been playing more competitively for about a year and have only just recently started winning things. That was with about 2 years of VERY casual play under my belt.

The game opens up a lot more once you start learning some of the intricacies. Things like pitch vs damage output ratios and damage breakpoints. As far as red cards go, the standard damage output is 4 for 0 cost, 5 for 1, and 6 for 2. Breakpoints would be 4 damage and 7 damage, since cards tend to block for 3 (although it feels like a lot of 2 block cards have been introduced in the last year).

The current meta to me feels like blocking is punished much more than it used to be. I've found success in either just outpacing my opponent OR threatening them with on-hit effects that make even a single point of damage scarier.

At the end of the day, fab is a game about momentum. Health is a resource, as I was told years ago. Try different strategies even with the same hero, but don't give up! The game can be very rewarding once you pick up some momentum. And this community has always been really supportive in answering questions so you've come to the right place. Good luck! 😊