When you are taking things apart make sure you have a spot to put screws. Something like an ice cube tray can be really helpful as it gives you a space to put the screws or other components where they are not likely to get lost. One thing you can do is number the slots in the tray then write what they go to on a piece of paper.
Another great idea is to take pictures of what you are disassembling. This is especially helpful if you have multiple cables that need to be plugged into something and aren’t sure where they should go back in.
Last when you are disassembling take you time and don’t rush. Use the appropriate tools for the job. Metal tools work but be extra careful with them. If there is a guide on iFixit or somewhere else, use it. If you can’t find a guide, take notes about how you disassembled something.