Thinking of learning registry editing by yourself??

I really hope you will not DIY it by yourself without someone who really know beside you. I have been trying to learn 'regedit' with my Windows XP this year. Not because of my curiosity but I want to know how to solve the problems left by the viruses or trojans from my friends' pendrives. What they always do is, change your registry, disable your task manager, etc. So, I would like to know how on earth I can change back the registry manually by myself. And the result is... Everytime I try on my own, I am sure that I will delete some important registry values, which cause my Windows can't even startup. All I do after creating such a mess was, repair my Windows(Just repair, not reformat okay....)...Hence, my conclusion is, don't ever ever try messing your registry without a proper guidance. In addition, don't just refer to the internet step-by-step methods, which can be not relevant or confusing for beginners. So, don't play play with REGEDIT!