Eye contact with a simple greeting goes a long way.
I know of only a few pilots who put only one application out there when they were looking for a job. Most of us could easily be working for a different carrier - it's just that our current carrier called first.
My point is that we all do the same job - just wearing a different uniform.
I'm amazed when I hear pilots take an us against them attitude towards other pilot groups. Maybe I don't understand why a pilot group is vilified based on airline management actions. Corporate cultures aside, we're not that different - think about how your life would be different if you worked for another carrier. There might be some pay and lifestyle differences but you'd be the same person.
I think the adage that you have to give respect to get respect. So next time you see a pilot that you don't know in uniform, any uniform, give 'em the nod. With what most of us have endured in our careers during the last five years - a gesture of kindness at work would be a surprise!