First things first. As with any new plan or change tell your family what you have in mind and how it will look.

Limit the amount of toys and books your kids have out at a time. I'd say 12 - 15 activities out per child, and a handful of books, more for older kids. Per Montessori training, children need to feel inner security and a sense of order to develop sound emotional growth. These characteristics may be fostered via a well-ordered environment.

A child's inner need for order will be satisfied when every item has its place and the ground rules call for everything to be in its place. Likewise a child's need for order is met through routine and predictability. Arrange stuff so that everything they need to do an activity is in a bin, basket, box or tray so that it can be carried easily to a play area and put away easily.

FYI, legos would be in one bin and limited to enough to have fun and be creative and yet still manageable to put away easily. So less for younger and untrained kids, increasing as they show they have the tools to deal with quantity.

Arrange the activities on separate shelves so that each child has their own stuff in their own area. In other words don't ask them to share toys, shelves/bins or play areas. Parents of younger children can consider putting photos or catalog pictures of each toy on the shelf to help.

Use toy chests and boxes for storage to put away the excess and if you are really organized, set up labeled, lidded boxes with seasonal items in either their closets, under their beds, in the garage. Rotate monthly and seasonally, more often in winter.

Initiate a one toy at a time policy. Take time for training and at neutral moments use roll play to show your children HOW to clean up: focus on one activity at a time, or toys of a specific color or type, or on a particular area. Make training a game and stop at a high moment.

Developmentally, toddlers from 18 - 36 months need to dump. Dumping is an essential activity in developing their gross motor skills, which is then followed by the development of their fine motor skills.

Instead of making available large buckets of lego, that will get dumped, keep the numbers small. A toddler is incapable of picking up 50 lego pieces in one sitting. Make sure to satisfy their need by giving children dumping activities whether in sand boxes, the bathtub or the kitchen sink.

In addition, per Maria Montessori, they need to exert MAXIMUM EFFORT, meaning they need to carry the biggest thing they can, dump the biggest, move the biggest.

And here is the FUNNIEST part: Play "Pick Up Bear" at least a full half hour before dinner prep begins. Get a big sack or basket, make up a "pick up bear song" and sing it in a "bear voice", you could even don a bear mask.

Invite your children to join you and pick up stuff. Any toys you pick up stay away for one full day. Present this in a fun non-punitive/threatening/competitive way, your kids will love it and your home will be neat and tidy.