OK, the first thing I'll point out is that you seldom make gains without risk, the trick is to minimize your risk!
Seriously, since you don't want to mess up your friendship then you should take things slowly. Just hang with her as a friend to see if the chemistry is really there. If it is you'll know it.
The downside to going about it that way is that she may wind up thinking friendship is all
you're interested in. That can lead to some painful situations for you.
Personally, I'd go ahead and tell her. Being up-front really is the best way to go.
Sometimes people ask for advice knowing what the responses will be, they just want to hear someone else say it. You already know the right answer, you just need to follow through and do it.