Well, that's straightforward. Friendships consist of intimacy and support.
Intimacy is about how close you are to each other. Friends know things about each other that most people don't. Your friends see you for who you really are and that's what they like about you. Most people have a deep need to be known. Extroverts often wear their heart on their sleeve, while introverts tend to open up to just a few people. What makes any friendship meaningful and satisfying is that connection. This is just as feasible online as in person, only the methods vary a bit. So if you want deep friendships online, then you should pay attention to what your friends share and tell them things about yourself. Think about the levels of online relationships. There are ways to increase intimacy and deepen friendships. Here are some questions for cultivating connections.
Support is about how useful you are to each other. The purpose of relationships is to make life easier and more enjoyable together than it is alone. Exchanging favors creates a balanced relationship that brings people closer. Meatspace and cyberspace each have different sets of support techniques, but both have good toolboxes. To deepen a relationship, offer to help your friends with things and ask for help when you need it. Validate their experiences. Say nice things to them.
Making friends online isn't that different from in person. First, find a venue that is likely to have people you would enjoy. Browse around and find some potential friends. Let them know you find them interesting. Use the venue's tools for "friending" people. You can also exchange contact information. On Dreamwidth, join communities and then visit the blogs of people who make insightful comments. Subscribe to their blogs. On your own blog, make at least some posts about yourself to help readers understand who you are and what you care about. Then build on common ground using the skills of intimacy and support.