There are a various ways by which you can save your hard disk. Various settings in windows consume a lot of space on your hard disk.
System restore is one which will consume a lot of hard disk space. It takes away from around 10% to 12% of the hard disk space. So in it is not needed disable system restore in drives which do not contain important data. However it is recommended to have system restore enabled for the primary hard disk so that you can restore your system in case of emergencies.
Defragment your drive once in a month at least. This helps to boost the system performance.
Disk cleanup is another process which will clean up unwanted temporary internet files and temporary files created by your browser and other applications.
Here is a good defragment application:
Recycle Bin is another program which consumes a lot of space to store deleted files. By default the size is set to around 10 to 12%.just configure the recycle bin to take only around 5% of the hard disk space to increase performance.
You can also compress files to save a lot of space in your hard disk.