When the aMule window opens, click the "Preferences" button:
On the right toolbar, click on "Connection." Set "Upload" to zero kB/s:
Under the "Files" taskbar, ensure that "Add new shared files with auto priority," and "Try to transfer full chunks to all uploads" are unchecked:
Under the "Statistics" toolbar, ensure that uploads are set to the minimum. In the case of aMule, the minimum is 3 kb/s. To avoid uploading, you can cancel uploads in progress on the home page:
Under the "Advanced" taskbar (on the right-hand menu), drag the slider bar to the farthest left. This will, to the maximum extent allowed by aMule, limit uploading: