There are a few ways to declutter a closet and pare down your wardrobe, though some are much more involved than others. As fall approaches, why not try a simple one? The hanger method takes a little time, but not much effort, and by the end of the season, you'll have enough hard data on what you really wear to make some choices about what you should keep.
This is an old tip that has stuck around because it works: Take every hanger in your closet and turn them all so they're facing the same way. Basically, make the hook on every hanger face the back wall of the closet. That's really it, as far as first steps go. Then, set a period of time, like a month or three months, and during that time, any time you wear something and hang it back up, turn its hanger around. If you wear it again, don't turn the hanger back to the starting point direction; keep it facing the second direction. At the end of your pre-set time, pull out anything on a hanger still facing the original direction and commit to donating or tossing a sizable chunk of those items.
Though it takes a few months to come to fruition, this is a relatively easy and data-driven way to weed through your clothes because it helps you see exactly what you do wear and what you don't wear. Actually being able to see which hangers were untouched in that time will help you figure out which clothes you don't really need, or at least which ones you should rotate to the front of the closet so you wear them.
Be advised that how well this works depends on a few factors. For instance, you need to give yourself a long enough time frame to do this that you actually have a fair chance at wearing the clothes. That's why I recommend doing it during a full season, like fall: Over the course of three months, you'll have enough time to wear work outfits, leisure outfits, and probably special-occasion outfits, so you'll really get to see some hard data, as opposed to giving yourself a month and only seeing a handful of worn items.
Second, it only works if you commit to decluttering once you've reached the conclusion of the experiment, so pull out some other decluttering methods when you reach that point. The five-second rule works well here. Pick up a piece of clothing you didn't wear, give yourself five seconds to determine if you want to keep or donate it, and then act quickly on your choice.
Finally, this can be combined with other organizational methods with a little effort. If you're using tiered hangers to save space in a small closet, for instance, be careful that you don't spin the tiered hanger around when you get clothes off it, confusing the direction your worn and unworn clothing items are facing. You can also try it with hanging shoe organizers or shelves within the closet, turning the shoes or clothes one way to start and flipping them around after you wear them. If you do that, try to write down the original and new directions somewhere, like a note in your phone, so you stay on track and don't get confused.