Consider first what you want to put up there, how heavy it is, how often you’re going to want it, and how you’ll get it up and down.
I have some high storage, and getting stuff up and down is a hassle, so only stuff that I’ll only want every year (or longer) goes up there. Outdoor Christmas ornaments are a good candidate, you only need the box down once, and they’re bulky and lightweight. Something like a lawnmower that you’ll need down every week, that’s heavy, bulky, and awkward, you don’t want to put up there.
I‘m also not a fan of depth. If I have to take down six other bins to get to the thing I want that’s behind them, that’s annoying.
Lay out what you think you want to store on the floor underneath the area. Now imagine putting up and taking down, from a ladder. Can you? Is it something you’ll want to do often?
Seconding the research recommendation. Find out what’s on the other side of that ceiling, and what load it can support. Just because you can build it doesn’t mean the structure can hold it up.