Retro Speedrunning- How Do You Do It?

I've always been interested in speedrunning as an avid collector of retro consoles (never enjoyed emulation much) and wanted to try to get into submitting times and sharing runs, but I'm not sure where to start tech wise. Is there a solid capture card out there that people are using for component-based consoles (i.e. Sega Saturn, Nintendo GameCube, etc.)? Would I need anything else?