I wrote before about starting decluttering for the first time. After you've been decluttering the areas that are the most obvious to you, you start to feel better. Free-er. At this point, having a plan to keep decluttering will make the most of your momentum and the most of your efforts.
I'm actually not a big fan of plans. I struggled with the idea of having a menu plan (I love it now, but I did struggle). However, I found that having a plan was better than not having one. I waste less time and less food by having a plan. I don't have to like it, but apparently I have to do it.
Make a plan. My plan won;t work for you, and your plan probably won't work for me. That's ok. You don't have to live with me (unless my kids are reading this), so your plan should be different.
Pick a starting place. Pick something easy. Pick something ugly. I like to start with the kitchen, because I use it every day. Decluttering the kitchen it too large for one start, so pick a part of the room. The pantry. The cupboard where you store appliances. The drawers next to the stove.
Get a couple of boxes, or a couple of paper bags -- something that stands up. Plastic bags lay there, and you either have to open them each time or they get buried under the clutter. You don't need your life to be more difficult. Get one box for Things that Go Elsewhere, and one for Things That Go Away.
Once you've picked a starting place, evaluate everything in that area. Pull out each item. It might help to set up a card table, so you don't have to put everything on the floor. I'll say this again -- pull everything out. As you pull things out, decide if they go elsewhere or if it goes away. Elsewhere could be returning something to another person, of elsewhere in the house. Your sweater probably belongs in the clothes closet, not the linen closet. That baking pan needs to go back to Mom. The shirt that never fit correctly goes in the "Go Away" box. The shirt you wear every time it's clean goes back in the closet.
It is so easy to flip through your cupboard and decide you like and use everything there. But it almost never fails that I find things that I don't want or use when I pull everything out of an area. I find books I didn't realize I still have. Or books that no one in my house actually likes. I find beans that no one cared for (they can go into chili), or food with garlic or allspice (they are migraine triggers at my house) that need to be passed along to someone else. So you really, really have to take everything out of the container.
Next, put everything back neatly. Put the skirts with the skirts, or the work clothes with the work clothes. Whatever makes sense to you. Don't color coordinate everything just because your mom told you it looks better that way. Organize things according to your own brain. If you like keeping your pasta and your canned tomatoes on the same shelf (because you make spaghetti marinara every week), then go for it. You may need to borrow things from other shelves to put them in the order that makes sense to you. You have my permission to mix things up the way they work for you.
Last, deal with the boxes. Put away things in the "Elsewhere" box as best you can. If you have something that belongs to your brother, start a bag of things that go to his house. Then deliver it the next time you see him. I like to carry things around in the car so I don't forget. I will keep a bag of books for my mom in my car for a week so I don't forget it at home when I see her. (Sometimes I forget it in the car. I'm just doing the west I can.) Write yourself a note, leave a reminder on your phone - do whatever it takes.
If there are things in that box that go elsewhere in your house, decide if you really want them, then decide where they should go. Don't put them "away" if they really don't serve a function. The sweater that has been in the hall closet -- if you haven't missed it, do you really need to keep it? Don't mess up your clothes closet with things you find elsewhere if they're really just clutter.
Take the box of donations away. Put it in the pile outside the front door if you've already called for a charity pickup. If not, put the box in the front seat of the car, so it will be annoying enough for you to remember and drop off the next time you're driving.
Only when you've completed the first area may you move onto the next area. Pick an area directly adjacent to the area you just decluttered. Do not move on until everything from the first area is cleared away. The last thing you want in clutter all over the floor, or shoved back into the cupboard or closet because you got too tired to finish. If you've set aside the entire weekend for decluttering, good for you. If you've squeezed in a half an hour after work, good for you. If you move forward from any spot and continue to declutter adjacent areas you will eventually uncover everything that needs attention. By working at your ability level, whether according to physical or temporal constraints, you can declutter everything you need to without making the mess worse.
I know this is really long, and I appreciate anyone who has read through to the end. Decluttering an entire home is a big project, and it needs to be addressed in steps that are not overwhelming, or it is too easy to give up on your goal of a lighter, easier home.