SWN seems to meet the old school halfway with XP by detailing how many points each class needs to advance, but not specifying exactly how you earn those points. It suggests you (the player) talk to the GM to find out how they are earned in the campaign.
I of course, have started my campaign without even thinking about this. All I do know is I don't want to award it for kills in random encounters - a patron enlisting the party for bounty hunting/xenopest clearance/trophy hunting is of course fine.
Any ideas for what to award XP for in this system, and how much?
Award xp for goals achieved, then. I believe it would be difficult to award xp for one type of combat and not another. It wouldn't make sense to me. However, awarding it for "treasure" recovered or spent or for "mission completion" would allow for a variety of situations.
This recent blog entry (http://therpgpundit.blogspot.com/2015/03/i-might-never-use-d-xp-system-again.html) is relevant to this, in some ways.
In SWN I award for jobs completed and goals achieved.