For first-time travelers, I always recommend Southeast Asia. This is the most friendly region in the world as people are used to Western visitors. People are very warm and welcoming and you'll never feel alone! Another option that I would suggest would be South America. Everyone backpacks in South America so you will always find fellow travelers to go with. I traveled 3.5 years from Mexico to Argentina and this is one of the highlights of my solo travel life. I also became fluent in Spanish along the way!