Let people know how YOU feel. Basically if you want to show people that you're sensitive to have to open yourself up to them as well. Sure, you can guess, but remember that you are only guessing. The 'mind-readers' just voice their concerns and thoughts, that's all. As for getting people to opening up - share activities with them, get to know them better, most importantly, share your feelings too.
Real concern helps too, as does a willingness to help out.
Best advice I know of is to honestly care about other people. Be friendly, honest, and open, and you will develop the friendships you want. Be consistent, so that people can see you can be trusted, and they will begin to open up. Above all, be there when your friends need you. That's exactly the way how it works.