I actually started out on this journey when I was an Army wife. I'm since divorced, but I'm still working on that since we've moved frequently in trying to get our feet back on the ground after our divorce. It's really easy to downsize with each move, but I wanted to do so much more than that.
One suggestion, have a friend come over and keep you motivated. That actually really helped me. We were going through the stuff in one of my closets. She'd pick up each thing she came across and say, "When was the last time you used this?" If I thought too long about it, she'd toss it in the bag saying, "If you had to think that long about it, clearly you don't need it!" It was so much easier to go through it with a partner because she kept me really honest about myself. She was also really supportive and encouraging. Whenever I'd hit something I wanted to give up but wasn't sure I was ready to, she'd always snatch it up, toss it in the bag, and remind me that I didn't have to worry about it, because if I was thinking I should get rid of it, then I should. I can't even tell you how much tat helped!
I also have picked up a habit of going through the things in my house about once a month, though we've had a lot of bumps along the road on that. We've had a lot of stress and change in our lives, which has thrown me off for a while. Still, once a month I assess the toys, clothes, etc and see what isn't getting as much use as it could. The toys I find go away for a month, and if the kids don't miss them, they're gone for good. With the clothes, we keep it to 7 pairs of pants, 7 pairs of shorts/skirts, 7 long sleeved shirts, 7 short sleeved shirts or tank tops, 2-3 sweatshirts or sweaters, that kind of feel. My daughter also gets to keep a couple of dresses, if she actually wears them. She also gets a couple of pairs of leggings to wear under skirts to keep them appropriate. My daughter and I have to go through her clothes again because she keeps being given things so she's got way over that again. We weed out anything that's torn, anything that doesn't fit, anything they don't like so much. I'm about to start the habit with clothes of any time a new garment comes in, an old one goes out, aside from with my boyfriend, but that's because he's difficult. I have to let him come to that on his own. That's kind of how we've handled everything. Now that life is starting to settle into a routine, I'm going to set it up on weeks for rotating through things, one week toys, another clothes, then health and beauty/cleaners/etc, then kitchen stuff and pantry supplies. It's a great way to assess what we need to replace and what we no longer need. Then hopefully we'll hit the point where we can completely take toys out of the rotation since we'll be in a much better position to keep on top of it.
Sorry this is long. No idea why but I'm extra wordy lately!