Nothing is organized in the Philippines lol. My experience is that most apartments/houses advertised on social media, (not all but most) is overpriced and "leftovers". When I moved to Dumaguete area from Bohol I rent an apartment in a resort temporary and was around on bike nearly every day in the areas I find interesting, to see if I could find anything which fit my needs. Talk to people around and ask in social media as you do and look around yourself is the way to go. You need to mention if you look for a furnished place, they are good places around just hard to find for a newbie to Dumaguete, but I think many in this site can help you with good info, good luck with your search, important to live in a place where you feel comfortable