Remove everything from your wardrobe and place it into a massive pile. Then make three piles - keep/donate/throw away. Then go through each item individually and ask yourself if you like and enjoy the item (if not, get rid), whether it fits/is comfortable/makes you feel good about yourself (if not, get rid) and if you’ve worn it recently (if not, get rid). You need to be brutal! Then with the three piles you can put what you’re keeping back in the wardrobe and see what staples you’re missing. If you want to be super organised you could sort it by coats/jackets/t-shirts and colour order everything. Hope that helps!