.asi scripts go in the main folder.
You need ScriptHookV to run these
ScriptHookVDotNet scripts go inside scripts
You need ScriptHookVDotNet to run these
ScriptHookVDotNet requires ScriptHookV
RagePluginHook scripts go inside plugins/
You need RagePluginHook to run these
Some scripts come with their own folders, there isn't any set rule as for where the script expects its data to be, so always follow per-script instructions or use the original directory tree given to you in the archive.