Handling two at the same time requires a lot of skill, there is a risk that while one is pounding me and making me enjoy the other one loses control and releases all its load in my mouth.
That all depends on the force of habit, when I give someone a blowjob I do it with all the passion possible, I want them to enjoy it exactly as much as I would like them to make me enjoy it.
When she does, you should start by having her wear a miniskirt with a micro thong. Then, when she feels more confident, have her go out without panties.
If she's okay with it, all you have to do is bring out her naughty side, just like my dear hubby does. On summer evenings, he takes me to the park, first getting me worked up to the point of giving him a blowjob, making sure some voyeur enjoys the scene, then he starts rubbing my clit, and my mind shuts down with lust. I'm so greedy to enjoy that I don't even look around and find myself sucking throbbing shafts and getting cumshots on my face without even knowing from who they are.