How can I maximize closet space?

Really depends on the size of the closet.

First, sort out all your clothing & get rid of / donate anything you no longer wear. Inventory what's left to figure out how much horizontal hanging space you need for blouses/shirts/pants & have 2 rods - one above the other - for those. How much space you need for longer items, like dresses & coats. How much vertical shelving, depending on what you want to put on it. Mine used to have folded sweaters & sweats on the shelves, now have labeled plastic shoe storage boxes. A shelf (or more, depending on how high your ceiling is) above is handy for out of season items (bathing suits, boots, white shoes, etc.) And if the closet has regular doors rather than folding ones, hang those multi-pocket shoe bags on the back for all kinds of things - socks, gloves, small purses, rolled up belts, hair accessories - whatever.

Rubbermaid has a great closet system called Configurations . Has accessories to it as well. I found them useful to add and change space in closets in my older home . Closets were small.

I put a metal shelving unit inside my closet. I use baskets to organize things on the shelves. Ikea makes a small inexpensive metal shelving unit that was perfect!

We got a shelving unit from Home Depot, lots of different areas for hanging and shelving and easy to customize.

Work vertically! High shelves are perfect for infrequently used items.