It depends on what ou think you may need, the above are very good suggestions for a regular jaunt, if you were going on a long distance tour then a few more spares would be in order.
In no particular order
Puncture repair kit
Tyre levers
Wire
Gaffa tape
Tie wraps both plastic and metal
Selection of wire
Basic spanners
Plies
Feeler gauges
Wire brush
The list could go on but a small tool box should hold enough tools to carry out basic repairs.
Try servicing your car and see what tool are required, that should be a minimum to carry.