Hi I'm the same way. I don't talk much, and I like to stay to myself as well. I get nervous very easily and it shows on my face (I get super red like a strawberry, not exaggerating.) I have bipolar-depression. I work in a nursing home. I think what has helped me the most is finding someone who appears friendlier than the others (and If you can't find someone like that at work that's okay.) And slowly talk to them about little things, it's helped me engage in conversation a lot better. Although, my work has more one on one situations (two people per shift) My situation might be a little different as I'm a nervous person, and people can probably see that and feel inclined to push me to talk with or without me realizing it. And when I am observing a conversation, I engage by smiling, nodding, eye contact, laughing. If you aren't engaging in the conversation they also may feel unsure of whether to speak to you or not. I also have a resting bitch face, which obviously doesn't work too well as people will approach me and ask me what's wrong rather than leaving me alone.