@Butrflynet,
Butrflynet wrote:
Ask her out in person. Then say you'd like to take her out again and ask for her phone number.
This^^....
Take her out to someplace modest: a nice coffee shop for a cup of coffee or tea. Talk to her. Offer her your phone number first. If there's a mutual connection, she'll offer her number in return.
Either way (whether you ask her to coffee or not), connect with her on a casual level. Talk to her but life in general. Commiserate with her about work but don't overdo it.