If you're not sure what your female partner is into, it never hurts to ask. If this is a first time or casual encounter, you can fold the questions into foreplay. Ask them what they'd like you to do to them or what they'd like to do to you (though if they're keen to dominate you, they'll probably let you know soon enough). If you're in a relationship, you can ask them pretty much any time. Well, not necessarily during, say, a beloved aunt's funeral, but use your discretion. You can chat over breakfast before heading off for a distracted workday or send them a flirty text on your lunchbreak. Encourage your partner to be open by saying you're keen to improve. A willingness to learn is very attractive.