Your tenants are responsible to maintain your property in as good a condition as possible. This means that they should use the structure and appliances carefully and as they were intended, meanwhile keeping everything reasonably clean. This also extends to your tenant's family, friends, guests, and their pets.
Any damage done to the property is the tenant's responsibility to either pay for or repair.
Some tenants will offer to make repairs themselves, to hire someone they know, or get a family member to take care of something for which they are responsible in order to save money. You have the right to say no and hire your own help or do the work yourself and charge the tenant. If you want to let the tenant take responsibility for repairs, depending on how major the work is, you might want to ask for references so that you are satisfied that the work to be done on your property will meet the standards you desire. You may also want to check your insurance policy for liability issues. If tenants, with or without your permission, make repairs or improvements which leave your property in unacceptable condition, you may have it repaired again either at that time or at move-out time be compensated financially.