If you aren't interested, no need to click.
If you are interested, I will be adding to this post during today - I don't have time to put the whole first post down now.
Also, I'll cover one step per post. For today:
First, determine exactly what you need:
1. What do you want to store? Boxes? Books? Seasonal things like Christmas decorations? Maybe you just want a place to display keepsakes? Or maybe you aren't sure - you'll just add whatever seems to fit after the shelves exist.
2. How wide and how deep do the shelves need to be to conveniently store the items? Are your decorations in Rubbermaid totes, or other standard size containers? Are your boxes cardboard or plastic shoe boxes? Are the books you're storing all paperbacks, or a variety of sizes?
3. How much of the construction are you willing/able to do yourself? How much money can you afford to spend?
3a. Top scale, you can hire someone to install custom shelves exactly where you want them. In that case, you aren't reading this.
Second, you can buy ready-made. You don't need my help for that, either.
Third, you can make your own, custom size and fit, and probably spend the least amount of money.
My project will be for generic storage shelves for Raederle's apartment. They will be visible, but six feet up, so they don't show much. In other words, they need to be moderately nice, but looks aren't critical. Storage is.
She will be putting any number of unrelated things on them, most of which is not used often. They will make two rectangles all the way around a rectangle that is about 5 x 10 feet, a narrower shelf above a wider one. Another factor is that two of the walls, facing each other, are slanted because they are also attic roof.
I will be using the cheapest materials I can and still have a sturdy, useful product.
Next up: Planning the lumber.