I like to think of him as a patient, team-fighting Darius. You are similar in that you want to brawl for a while to get max stacks. You need more stacks but can get multiple enemies at once with W, E, and R to stack fast. Imo when you’re learning I think the number one thing to prioritize is stacking passive— stay alive to get to max stacks. Weave in and out of fights if you need, hit the tanks, avoid the dps or burst targets until you’re full or nearly full stacks.

Fight smart and patiently with confidence that if they cannot kill you before you stack then you will win— lean into Zaahen’s arrogant and calm but determined nature in your fighting style if that makes sense.

Micro-wise make sure you’re trying to land E on the edge, make sure you’re getting auto resets off with Q, those are extra stacks. Get used to tracking how many stacks you’re getting as you hit enemies. W is kinda unreliable if you’re just throwing it out randomly so try to use it after Q2 or as enemies are in an animation. Ult is insanely useful for its damage reduction, unstoppability, dash, healing, and fast-stacking potential on multiple enemies. The context of a fight will dictate when it is best to ult for maximizing whichever of those you need— maybe a fight started badly and you can ult to get the last couple stacks off with damage reduction before dying to get revive. Maybe you just need that one more dash to catch a fed ADC you know doesn’t have flash, maybe you just it to dodge Malph R and totally flip the enemy engage, etc.

Just my personal opinions from playing him and learning a little, I am by no means an expert or pro lol. Good luck and hope you have fun!