@Philippe Ueng, I see that this is your first post - welcome to the Bigger Pockets community!
Since you are asking for general advice on out of state investing, here is my two cents worth...
I agree with @Hattie Dizmond, you need to have a reliable team on the ground to be your eyes and ear. In addition, know something about the market in which you are investing. To make the most knowledgeable investment decision practice what is taught in the Toyota Way - genchi genbutsu, which means "go and see." If you are really interested in a particular market go visit it and meet with potential team members (realtors, wholesalers, contractors, property managers, etc.).
Having an intimate knowledge of an area will lead you to making the most profitable decisions. Even in our hot market here in DFW there are places that are not experiencing appreciation. For instance see the article from the Dallas Morning News (www.dallasnews.com/business/residential-real-estate/20160204-where-home-prices-are-rising-the-fastest-in-d-fw.ece) noting the area on the map that had decreasing prices. These changes happen both on the macro and micro scale. Also note that more than a third of the purchases in 2015 in moderately priced areas were to investors. It is a very competitive market, with these homes being on the market for only a day or so.