You might need a fire extinguisher - that makes your plane much safer
and maybe maintained in accordance with the aircraft and component manufacturer's maintenance manuals - so (E.g) ADENG4 will not apply, which some LAME's seem to think is a legal way of running an engine 'on condition' but only if not in charter. (I think that means past TBO and/or calendar time, which for example, might be 2000hrs or 12 years for many Lycoming engines). You won't need carriers liability insurance unless its actually used in Charter and then its the operator's problem who will need a Charter AOC with that particular aircraft type mentioned on it.
Always struck me as a bit strange that an aircraft maintained with components 'on condition' is OK to carry unsuspecting people for private flying and training but too dangerous for charter.