The direct answer
Do not mash every available attack. Tears of Metal rewards readable chains: keep enough space to see telegraphs, commit when the target is exposed, and preserve dodge or block resources for the next dangerous cue.
As of version 0.8.57278, boss block-breaking attacks can be parried. That makes a confident parry a real offensive answer, but missed timing is still more dangerous than a safe reposition.
Combat priorities
Remove ranged pressure and disruptive support units before they force you to spend defensive resources.
Use light attacks to maintain tempo, heavy attacks when the target is committed, and finishers when the chain or upgrade effect makes the payoff worthwhile.
Watch interrupt power and resistance. A high-damage hit is not automatically the best control option.
Treat perfect-dodge and perfect-block windows as build triggers. Many upgrades and Charms activate specifically after those events.
The launch patch renamed Kill Streak to Chain Streak; older wording in community material may refer to the same mechanic.
Use exact values
The Attacks & Combos catalogue exposes base damage, damage type, sequence type, interrupt values, ranges, timing, block multipliers, and linked users where the static build defines them.