Well, if you have ever seen her flirting with a guy, then you shouldn't approach. But if tyou have never seen it, talk to her and see how she reacts. Get to know each other, and go on to a few occasions together as friends. Be open, supportive, and wait to flirt her until you are comfortable she's interested in you.
If you don't feel confident enough to do that, you can be blunt, and ask her outright. But like you said, you don't want her to be uncomfortable.