When to delete old files and create System Image after System Repair

I have just finished a System Repair on my Windows 7 using repair ISO, and I'm not sure if I should do a system image backup before deleting old files with Disk Cleanup, or delete them after I've done a Repair Disc and System Image as well. I'm also afraid to delete anything at this stage. Would it be safe to delete Restore Points and Shadow Copies at this stage (I only did repair today), or should I wait a week or so?
I guess what I'm asking is when and what to delete and when to create a System Image and Repair Disc. New to all this and don't want to muck it up, so any help I can get would be very much appreciated. I have printed out your tutorials to follow on Disk Cleanup and removing $Window.~Q file.
Thank you

Thank you so much for this quick reply. I will now confidently do all you said.
I love your quote at the bottom of your post - makes me feel better and not so much of a fool.