Help me understand how to use shield properly

I'm about to start a third playthrough of elden ring, and I want to try shields but they have never really clicked for me. I feel like every attack that I see coming and are able to respond to, I'm always just better off Dodge rolling in stead of blocking. There's just something in the gameplay loop where just the fact I'm consciously trying to remember to use my shield takes my attention away from actually playing well.

I'm planning to use the brass shield mainly. Paired with the partisan/bolt of gransax once I reach Leyndell of it helps.

So as the title says, what should I change in my mindset/way of approaching encounters in order to actually make good use of a shield?