There is low technology and high technology.
Low technology could go all the way back to the caveman chipping pictures into stone, but more than likely it’s pencil and paper. Simple, no power needs and available almost anywhere. Sometimes the simple solution might be the best. Higher tech from this would be substituting a pen for the pencil. We’ve been trained to use this type of technology for most of our lives. Downsides would be the inability to easily share, legibility and durability.
High technology solutions would include laptops, netbooks and tablets. Dependent upon the type of software, note-taking could be done in outline format, visual mapping or some combination. Pro’s would be easily shared, legible and easily backed up. Downside would be ease of use, loss of power and unfamiliarity with the technology.