Starting a project that requires removing a number of small parts and plenty of nuts, bolts, clips, hoses, etc.?
Pull out your trusty camera and photograph everything from several angles BEFORE taking it all apart. As you disassemble, place the parts in clear ziploc-type bags and toss a piece of paper in with a written description of what the part is. Reassembly will go far smoother.
If you're involved in a major car restoration, devote entire shelves to similar or related parts, to help keep things orderly and under control.
Keep all parts, no matter how bad they are, until you have a correct replacement in hand. In fact, if you have the room, keep old parts until the new ones are installed and have proven to function correctly. The older these project cars get, the harder it may be to source some replacement parts and you may have to restore the original parts.
During disassembly, if you take the time to clean, check and test each part, it will prepare the way for an orderly reassembly. It will also give you much more time to source replacement parts as you disassemble rather than trying to find everything at the end of the disassembly stage.
How do I know this stuff? Once you've spent 4-1/2 years on a complete rebuild project, you learn a few things.