@Joanna193 As a new host, or even an experienced one, a 6 month booking is not advisable. What if you end up not being able to to stand this person? What if they are filthy slobs? What if they turn out to be one of those people who seem to break everything they touch? 6 months is a long time to have a stranger around. Airbnb really isn't set up to protect you as far as long-term bookings go. If you were going to rent to someone for say a year, wouldn't you want a lease agreement, references, work history? Most landlords would. Airbnb doesn't seem to be able to even filter out people with criminal histories.
Now, if in the future you have a situation where you have a guest who has already stayed and they were wonderful and trustworthy, and wanted to book your place again for a long term, that would be a different scenario.