It really depends on where you work, and who they are( I myself am an Aspie). I work at a fast food establishment, which means very short and noncommittal bursts of conversation, which I can manage. However, when I have no pressing duties to perform and I am stuck trying to converse with my coworkers, I inevitably fall short. At least in my case, I find it especially helpful if I am not pressed for conversation. If I need/want/am able to communicate, I will. But that's just me and the food industry. Basic guidelines that I think work in most contexts: 1) we are human, and thus do not like being treated like babies. Give us the independence that everyone else gets. 2) if you want to appear affable and friendly in a closer sort of way in attempts to create lasting friendship, learn about what we love. There is that niche of things that we can and love to talk about that varies from person to person. we(at least, I) do not have a very precise model of social mores and rules, so conversation is hard. By allowing us to talk about something that we actually can talk about, we can simulate actual socializing(This is time-consuming, and we could go on for hours). 3) don't be afraid to ask what our boundaries are. It varies wildly from person to person, so learn the person rather than the disorder. Some of us are more neurotypical than others, some of us may be trying to train ourselves to be closer to the norm(in the social aspect), and some of us may have given up on social constructs completely. I can't stress enough the variety present in the ASD community, so focus less on labels and more on personal preference(For example, I despise bodily contact, but others may enjoy it, even though a "sign" of an ASD is the aversion to bodily contact).
Again, this is just me. I am rather new to this, as I just found out about my Asperger's 7 months ago. But assume nothing, and keep an open mind. If you notice something bothers us, stop it and don't take it too harshly if we tell you to stop it.
That's the best I can do. I hope that helps.