While there are tools to do this, be sure you backup the drive to some image file first so you can recover with ease.
With that out of the way I like the following.
1. Be brutal and uninstall all apps you haven't used in 1 year. 6 months. 3 months?
2. Try CCLEANER. Do not change from its defaults and only use the file cleaner.
3. OK back to hard disk work. Backup the image for free with CLONEZILLA. No tutorial from me as there are plenty out there.
4. With step 3 out of the way I can boot GPARTED to shrink D, move D to the end and extend C. Again, no tutorial from me since there are many out there.
Hope this helps,
I use an Acer Aspire 5710 laptop which came with 120GB hard disk drive already partitioned at 52GB for C drive and 52 GB for D (data) drive which is used for backup. Now the C drive is full mainly from updates (300MB free) while D is 35GB free. My computer is very slow and hanging most of the time.
Is it possible to add some of the space on D drive to C drive? What can I do recover space on C drive? I have uninstalled most of the programmes from my computer yet no free space. I have since disabled windows updat.