Say, when I'm chatting with friends about their problems, I tend to say "I think" "I don't think" "I don't ~" "You should" "why don't you ~" etc often. I didn't mean to force them to do what I say. I always mean to sound softer and nicer. I don't want myself to sound I have a strong opinion. At the same time, I don't know where to solve the problem as long as I'm a self learner and no partner around. Chatting online is never as same as a face-to-face talk. Ps. As you can see, I'm using a lot of "I don't" and sentences with "I".

Starting a sentence when you're talking with somebody whether it's in person or messages usually is okay. I guess it just depends on what you are saying. Could you give an example of what you mean?