if she comes with clit stimulation, and you provide that with fingering or tongue, your job is done. remember you can make her come multiple times. she will definitely stop you when she gets too sensitive.
do you know where her g-spot is? a hook-like rubbing of that can also make a girl cum, or at least get her very very horny.
untested (yet.. it will be tested tonight though

).. fuck her doggie-style and have her rub her clitoris, directly or with a Magic Wand if she has one
you could ask her to finger herself to orgasm (if she is into that, most girls are, but many will deny it) and learn the way she does that, then reproduce it
the pillow is good, but some girls will not come even that way.. just enjoy the experience more, and will appreciate that you care enough about their pleasure to plan for it
long eye contact, dirty talk and the own-the-pussy line might help out.. does she have a kinky side? you could try some role-play. guess what, most girls have a fantasy for being raped...
another common theme is spank her, treat her like a naughty girl and punish her
I am also open to more advice from other users, of course
EDIT: never, never, never, act self-conscious about you not being able to make her cum by penetration. it will only make her self-conscious and even more unable to cum. it's not your fault, it's just the way her sexuality works. as long as you make it good for her and she makes it good for you, all is well.