Any low light AF tips for XE-1?

Agree with MLYL. The autofocus prefers vertical contrasts to horizontal so try to find an appropriate vertical line to focus on or switch to portrait orientation to make the camera see a horizontal as a vertical. An alternative strategy is to set the focus to Manual. You can use AE-L/AF-L button to try to autofocus when the camera is in Manual and, if doesn't work on the first or second try, you're all set to use manual focus (page 42 of the owners manual).

Jeff