Be Sincere
Though at last paragraph, the first and foremost guideline for the owner of a/the vacation rental website is to really want to make people happy. Your main and sincere wish should be to make a guest’s stay as good as possible. Only then goes your wish to earn money. You should learn to listen and hear what your guests say or think. Remember that when a guest rents house for his vacations, he seeks good rest from work and day-to-day fuss and would not want this stay be darkened by any inconvenience. Love your owners! Love your guests! Love properties!
Highlighted parts don't quite flow in English. Some suggestions:
Though at last paragraph, the first and foremost guideline... - Last but not least, the guiding principle...
Only then goes your wish to earn money. - Making a profit depends on this.
learn to listen and hear what your guests say or think - You need to listen hard to what your guests are saying.
he seeks good rest from work and day-to-day fuss and would not want this stay be darkened by any inconvenience. - he wants a break from work and day-to-day worries. He does not want his vacation to be clouded by trivial inconveniences.