There are many ways to obtain back links. The most widely used method is to buy backlinks. There are many websites available which allow you to buy back links, but Google puts more value to editorial back links. One of the best ways to get editorial back links is to participate in the community. Scanning and signing a bunch of forums or blogs is not what is to be done but rather showing up a good example by answering questions is the best way to obtain editorial back links. If you have something of worth, some quality of appreciable nature, some value that you can add by answering questions and helping out others, many people will appreciate your talent and will link to your site. This is one of the most respectful way by which you can buy back links which are of very good quality. Just by participating in that community and being part of that conversation, people will know more about you as an individual and you will have a more positive connection with those people.