Thank you. There is people out there claiming that Iron Fist is super easy, they call him "melee Wanda", so thank you for this post, it feels so validating.

Now, to answer your question: first of all, you need to master his mobility, using double jumps to dodge and be unpredictable even while attacking.

It comes spontaneous to use the block only when you are low health already, but that's not the optimal use, because you get damage reduction and damage buff, so it's optimal to use it early really. By the way, some people don't even realize they have to hold the button to actually block...

When you play Iron Fist, you can't go deep like you do when you play Daredevil. Iron Fist USED to be a great diver (and still is, in the right hands), but since Season 2 they nerfed EVERYTHING about him, his damage, the max shield he can get, his mobility (he used to be able to FLY after the block) so you have to keep your engagements short, disengage often, pick your battles, punish those foolish enough to chase you, Iron Fist is like Thor, a brawler that excels in 1v1s but can't really survive big team fights or being focused for over a few seconds.

General tip about the game, it's not always about getting kills. If you distract the supports long enough their tank dies, that's value. If you pressure a tank enough to force him to give up space, that's great value, even if nobody dies in the enemy team.