I've written an entire novel in first person plus present tense, so I know a thing or two about this very subject. Fffffun!
And I mean fun, at least for me. The secret is experience. To experience the world from your character's point of view, wether he be good or bad, lol.
When we see the world, our brains are always analyzing everything and relating it to something we've experienced, even if it's subconscious. Much of the first person is largely subconscious analysis. If you can do that, not only are you explaining the environment, but by relating it to past things you're building the history at the same time.
Let's say there's a guy going through a mundane day, the ultimate non analysis routine. How do you explain what he's doing when it's all the same to him, right? You'll likely need to create a situation that sparks a line of thought.
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I didn't even hear the ring. I forgot what the alarm's tone sounded like. By the time my grey slippers hit the square doorframe, I couldn't even remember the color of my room. I think it was...blue.
Next moment I knew, my face was cold. I found myself face to face with a milk carton in the pale fridge. The Umata knew how to build their houses. Simple. Simple and pure, in every form, help keep your feet moving without any whatsits in the way. Who needs a television when you work? Who needs a new toy when the old isn't broken? Are we....?
...Mmm, I tasted cereal. I took a gander down and my hand ablidged to deliver the milk soaked cereal from stainless steel bowl to my ready mouth. My hand smelled like the chilling metal table.
My house smelled like garbage.
...Garbage? My body snapped out from my clockwork stare to find the garbage can.
Nothing picked up my garbage. My eyes blinked, as I realized I'd have to find out what happened to the company garbage bot.
I sank it into memory, slipped back into my clockwork routine befo...oh. I had already eaten my cereal.
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This is just something I wrote very quick, but an example. Someone loosing their humanity almost to routine, in a mundane world. If that can be written interestingly, you can certainly find a way to make your world very interesting. Even if it's something he's seen a thousand times, then it has history. Let that history cross his mind. Recall previous times he's had with that particular place, person, or thing.
I know what you'll ask. What if he doesn't notice something, or simply doesn't understand what he's looking at? Then don't write about it. Focus on what your character notices and what your character understands, then flesh it out by his Persona experience and USING ALL FIVE SENSES.
Your biggest tool. ALL FIVE SENSES. Smell, taste, touch...experience the world through that character's senses to build it. First person is less about the explanation and more about the experience.
As much as I understand this, I know it can be a difficult concept to really grasp, so if you have further questions, please ask. ^^;
