Kids' Rooms: Let's get shelves done first (if appropriate). Use same method: examine, toss/save/donate, replace onto shelves.
This is a good time to get rid of games with lots of missing pieces, or save for while you're in the playroom in case the pieces are hidden there.
Desk drawers: go through (or have your children if they're older) and sort out what papers need to be saved and what can be tossed.
Get rid of old magazines, old McDonald toys, toys in pieces, broken crayons, non-functional pens. make room for the stuff on top of the desk!
Clothing Drawers and Closets: Again, check for current sizing. Too small? Donate to a friend's kids, Goodwill, or homeless shelter. Torn? Can it be used for rags?
Box up anything to be saved for a sibling. Label and the box and put it away now. Throw out anything not able to be repaired! Have your child try on questionable items.
Before we go further. have you thought about taking curtains down, and washing? Better start now! Throw the bedspread & blanket in the wash too!
Time to check under the bed for the nasties down there. This might be a good place for under-bed storage containers.
Once everything is picked up off the floor, don't forget the ceiling fans, and wash your ceiling fixtures. Now's a good time for windows & blinds too! Don't forget to dust, & polish any wooden furniture.
If you have boxes stored in bedroom or closets make sure you have a good marker with you to mark the outside of boxes with contents.
(You can do this but I find that giving the box a code number, letter or name and not marking the contents directly on the box but instead on an index card placed in your SHE box, you can at anytime change the contents of the box without writing and rewriting on the box what is inside.
You can use the same methods for playrooms or play areas. Perhaps if you have a hobby room and no children, you can use this for your sewing or craft room.
If you have none of the above, then take a relaxing bath. Then go over any areas that still need "doing".