I haven't had too much trouble getting DD(3yo) to pick up her toys BUT I did start from when she was very little, telling her we have to pack away now and we would pack away the toys. As she got older she continues to do this as she doesn't now any better. I also don't let her get too many different things out at once. If I see she has finished playing with something which there are a fair few of and she gets something else out I remind her to pack away the first lot of toys. That way it is too overwealming at the end. In saying all that I have on occasion had to say if I have to pack up her tools they will be going to the children that don't have any, she packs up pretty fast then. I only ever have to say that once and as I said I haven't had to use that line very often.