I've read here and there that you should be ready to give before you need something from others. In other words, help people before asking for their help.
I just asked a favor from a department in my company in a hurry, and even though the colleague agreed to do the task (I was smiling and somehow open to discussion, being polite etc.), I feel guilty about that.
I asked him if he could do it top priority, I didn't use the ticket-tool we have for this kind of request, and he accepted only because he is genuinely nice. All in all, I was extremely lucky I could talk to this guy in particular, his coworkers might not have accepted my request (which is normal - it's my fault if I'm late).
How could I have help him in any way, when his department is out of my technical background, without being rude or anything while asking for a favor ?
Needless to say, if anyone comes to my office and ask for help I would immediately try to help him/her, or at least try to.
May be related: How do I thank a co-worker for helping me