I had a blonde friend who also fits the description of you gave of yourself.
Just incase you didn't know this, guys would rather get rejected by an average chick than a super pretty girl. She started approaching and befriending guys instead of waiting for them to talk to her.
Perhaps you are constantly staring at your phone and only looking up from time to time with a scowl on your face.
Some guys would certainly see this as intimidating.
If it is a guy that you actually find attractive, you can dwell for a little bit longer in order to let him know that you are interested.
The more you practice this on a day to day basis, the easier it will be to start doing this more often when you are around guys.
Yes, that means that you try paying attention to him and stay quiet.
You interject from time to time with follow up questions but you still let him continue expressing himself.
Actually give him the opportunity to talk and express his opinions.
Whenever you find yourself in this position where you are interacting with a guy, keep telling yourself to be patient and hear him out.