You might want to try making plans with him as friends first before asking him out romantically. Find something that you have in common, or a movie that you both really want to see, and invite him out. That way, you can see how you interact one-on-one, and get a sense for whether there is chemistry between you. If you do decide to ask him out, then you can start by telling him how much his friendship means to you. Be honest, and let him know what your concerns are. You could tell him that you feel something special between you two, but if you are mistaking strong feelings of friendship and he does not reciprocate the feelings, then you will understand. Always be honest and then he will feel comfortable enough to return that honesty.
