Being active in social media involves more than updating your status whenever you walk your dog or go for ice cream.
Being active involves getting to know people and letting them get to know you. You want to add value to their online lives.
Use the same methods you would in person. Ask what they do for fun, or about their jobs or family. Just get to know them.
Take an interest in people. After all, MLM is a people business. Take part in group discussions trying to add value to the conversation. Posts like "nice post" do not help.
Browse the profile of people you meet. Look for common interests or anything else you can talk with them about. People love to talk about what interests them, so let them. Ask questions and let them run with it.
You'll be surprised just how much you can learn.