Great post! Let me preface this reply; last year was my first year. I spent 9+ months here on eplaya and researching BM in general. Now I'm a regional contact and looking to (only) my second burn next year. I am not a "veteran burner" by any means and am still humbled by all that I do not know about this magical thing we do. That said...
The Burner culture of decommodification and the human acculturation in defaultia means that your awkwardness in understanding the etiquette at BM is not uncommon and actually may be shared by the bartender! Yeah, believe it or not we are all humans, conditioned to life where every interaction of goods involves an exchange, and it may be weird shedding that prescriptive behavior.
It was a little odd for me the first few times I walked into a bar at BM. Not because I wanted booze but wasn't sure how I should go about getting it, but because I was unsure about what was expected of me. I knew the usual tips you will read here; Don't walk in reaching into your pack and dusting off your cup expecting something, don't try to reciprocate a gift out of a sense of duty to exchange, etc.... But still, when you come from years of conditioning into a world of gifting, ie a world where people give to you because they want to, not because 1) you have something they want for exchange or 2) because they owe it to you to provide something (a la Rainbow land) you sort of have an odd time figuring out your role in this drama....
Here's the secret; There is no role, there is no drama... IF you choose to think that way. One way to avoid the awkwardness is to always have your own drink, that way you you don't have to care whether or not they serve you. Be on the search for a cool place to hang out. When you find one, hang out, enjoy it, share, socialize and come back again. If you appreciate the atmosphere the place provides you, donate something. Ask the bartenders what they need or might be running low on. If you can help, help. Believe me, if you do these things you will find that that bar is a huge part of what you loved about your BM experience. The fact that they have given you some booze along the way is almost incidental.
Relax, enjoy yourself, create, contribute and look for ways to help. If you do this every day you will likely find that by the end of the week you're looking for ways to get rid of the booze you brought because along the way you were given so much that you never really thought about what to do with what you had other than share it.
Nebraska Regional ContactTallgrass Burners - The Omaha and Nebraska Area Burning Man Regional Grouphttp://www.tallgrassburners.comEmail: nebraska [at] burningman.com