Was this seminar far away from both of your respective cities? Ask her out to discuss the seminar afterwards over a cup of coffee. Keep it light & good luck! Every relationship starts with a common point of reference; you seem to have a natural in already. Once you two start chit chatting, inquire more.
Find an excuse for her mobile number and text her outside of University or whatever it is you've met at.
It's not sly or anything. When she gets a text out the blue it's obvious you're thinking about her and it would be good to suggest something such as a coffee.
"Hi it's ***** from ur seminar group, fancy meetin 4 a coffee 2moro b4 the seminar?"
I've already confessed to Lit. I got my girlfriend's number from her cousin did the same thing and we've been in love for 5 months now It's just a case of taking a gamble. We had a quick chat she thought I was cute but didn't do anything about it. Next day that cute guy sends her message asking for her email, got talking more and we go out.