how to manage big project? I'm working on a room with lots of stuff. This project worries me as I look at the outliner's growth. I know in term of management blender's outliner is already pretty amazing but can you suggest any better way to reduce confusion?

for example when I make an indoor plant with a lot of leaves I'm gonna have leaf1, leaf2, leaf3 ...etc How do I get all the leaf into 1 one folder?

thanks a lot
Presumably the leaves will be part of a plant - in which case you'll want to set them to be Children of the parent plant. This way when you manipulate the Parent (eg, move, rotate, scale) the children will be similarly affected rather than being left behind. You can easily Parent objects by selecting all the children, holding Shift and selecting the Parent (so the parent is the last object selected) and then pressing Ctrl+P and select from the Parent menu. When you do this the outliner will show them as being within the parent object which can be collapsed to hide them (ie, the Parent effectively acts as a folder for its children).