It is best to arrange your insurances with your own insurance company.
Many travel agencies also offer to arrange an insurance for you, but often this is more expensive than arranging your insurance with your own insurance agent.
You also prevent problems by arranging your travel insurance and health insurance with the same company; when you have insurances with different companies, they can refer to each other the moment you want to claim costs.
This insurance reimburses the extra costs if an unexpected event would occur. It is also possible, for example, to insure the additional costs that would arise if you needed medical assistance during your return trip. Your luggage is also insured. Consult with your insurance company which policy suits you.
This insurance will reimburse the costs you are faced with if you unexpectedly have to cancel your trip due to urgent circumstances. This insurance is often offered when you book your trip, but also this insurance is usually cheaper if arranged with your own insurance company.
If you organize your trip yourself, it is most practical to have one insurance policy covering all the reservations you make, instead of insuring each booking separately.