what to clean first

So I have decided to finish my sons room first.  I started to clean and organize it on Friday but it did not get completely done.  This seems to be a running theme with me.  I started doing something but get overwhelmed and just drop it.  The problem with my sons room is that we get so many handme downs from everyone we know that I just sort of started throwing them in there.  So there are tons of bags of stuff all over.  Also that fact that he is growing like a weed and I have to change out his clothes it seems every month.  This little guy is getting huge.  So my plan is to take a picture before I start and than try to get it together.  As I said it was started on Friday so things look so much better than they did. I will post the before pics after I take them and will be keeping an update of the progress.  I think I need to start letting some things go.  This is so difficult for me as we are hoping to have more children and we are so thrifty.  I think we have saved so much by getting all the handme downs and I hate saying no because of how much it has saved us.  But I think I need to learn to get rid of things I know I do not need.  I need to start thinking on a simpler scale.  Cut back on what we have, learn to live with even less than we have.  So I am going to keep that in mind as I finish this project.