I really need to have a good declutter too.
I find that having a box under the bed for charity bits and pieces works - I pop clothes that we no longer wear in there, and once it is filled I bring it to the charity shop. It seems less daunting, and less of a wrench, if it is done on a gradual and ongoing basis. Note to self - do that today!
Our local recycling centre also takes larger bits and pieces which then go to charity shops, and I quite like the anonymity of leaving things in there.
Luckily, I have a couple of friends with younger children, so I can pass some clothes on to them, but I still have loads of baby equipment and toys that I no longer need.
Part of my problem is that I keep threatening to do a car boot sale, or put things on e-bay, but then never get round to it (have never sold anything on e-bay in my life).
It does help if everything has a place, and I tend to use boxes / containers within drawers and cupboards to sub-divide them - so for example, in my kitchen cupboards, I have boxes for rice & grains; flours; sugars; baking etc. Same for toys - IKEA do great toy storage.
My other secret weapon is to have a dymo label machine - I have labels in all my cupboards and drawers to show where things should be - e.g one drawer is 'PJs & fitness' etc.
Finally, if it is clothes that are lying around, why is that? Do you have enough room in drawers for everything to be put away? If not, you either need to get rid of some clothes, or get more drawers / cupboard space. We have a chair system in our house - everyone has a chair in their bedroom on which to put worn but still cleanish clothes that could be worn again. At the end of the week, everything gets thrown into the wash and put away. Laundry baskets in the downstairs cloakroom and upstairs also helps.