I want a bigger looking of folders, but the blank space between folders becomes big ,too. Is there any way to fix that?
Unfortunately there is no easy way directly in Nautilus itself.
You can however use
sudo apt-get install dconf-editor dconf-editor
Now navigate to org->gnome->nautilus->icon-view. Try setting bigger values in the thumbnail-size field. 128 worked for me. Don't forget to restart nautilus afterwards:
It's not a perfect solution as it changes only the size and spacing of pictures/videos thumbnails. Regular icons are unaffected, as their size is by default 48px.