Start with a clean working space. You can't get rid of clutter if you are doing it admist clutter. If your work space is cluttered, make that your 1st project. Put things you need to keep away, toss trash, put still usable things to giveaway in your donate box.
Have all your supplies handy. If you have to keep going back and forth, you may get sidetracked and not accomplish anything.
Do not stop to clean while you are decluttering. Make sure you have time to devote just to decluttering.
Don't take out more than you can do in a half an hour. Some people say an hour, but with 5 little ones, I don't get more than 30 minutes at a time to work on anything, even if they are helping. If I pull out more than that, it usually ends up creating more mess than was originally there.
Have your kids help you, even if all they can do is run from here to there putting things away for you.......hey, that's less running that you have to do and you may have energy to do more decluttering:)
Let your kids go with you if you are donating things to a shelter or other non-profit, especially if they can actually see the people they will be helping. Let them see that their unused stuff will make some other little girl or boy very happy.