Clutter often begins from having no clear place for a specific item, such as no spot to put gently used gift bags or extra birthday party supplies. Take some time to assess which items seem to be consistently out of place, and usually you will find that it is because they have no designated home.
Contain these items by starting with totes, boxes, or baskets. Clear bins that keep things visible, or have obvious labels are highly recommended! Once you place things in an opaque container, you are likely to forget what's inside.
Do you have a donation box? This is a great place for gently used clothing, toys, and household items. They can go here and when the box is full, it is time to take it to a local thrift store.
A resale/consignment tote can be useful if you plan to have a garage sale or sell items online. Keep these items together and out of the way until you are ready.
A question basket may work for anything that doesn't yet have a place, but don't let the basket overflow. Once it is full, that is a great reminder to create some homes!