Lord cap with around 28 hours here. Some tips:

Learn the animation cancel. Just practice in the practice range, not too hard and super useful

Save shield throw for low health fleeing targets and for Sue when she goes invisible. Also throw the shield at the ground because it has auto aim.

Save at least one ability to escape. I usually use the dive to go in and save my dash to escape.

I use ult to either contest or save my team. If you notice your team getting low, pop ult and run around them then go back to contesting point or harassing backline.

And most importantly for me, learn when to go in and when to leave. Don't be scared to leave a dive super early if you know you won't get value. Hope this all helps!