I know it's easier said than done but you have to keep the toys picked up and declutter as much as possible. The use of colorful storage containers and baskets can be helpful. Remember the old saying, if you can't see it, you can't sell it. Meaning, prospective buyers need to be able to see the floors, walls, cabinets, counters, etc. and envision what their things would look like there.
You may also want to think of implementing some sort of program for the kids so that they are involved in keeping the home neat and then have a prize or reward for each of them when your home does sell. That way they feel a part of the process.
Best of luck!