Having LARP'ed and even INGRESSed, there is a certain etiquette that players need to display. The entire time I have played, everyone I have encountered has been politely amused at worst, and many have been quite positive. However, there are certain unwritten rules I follow.
1. If your gaming takes you into an establishment, at the least browse their wares, at best BUY something. I was shopping for school supplies at Walmart the other day, and there were tons of good Pokemon around. Several associates asked if that was what I was doing and even joked that there were great Pokemon in that store, but since I was clearly shopping not a one was bothered at all by my gameplay. Several of the smaller establishments have commented (as I sat playing Pokemon while sipping a drink) that they would feel better about it if more of the people actually looked around or bought something. They don't mind the game, they just want to see it POSITIVELY impact them.
2. Don't block the main aisles, roads, or throughways. The game has a reasonable margin of distance, and especially if you turn off the camera, you have a lot of latitude with movement. Click on your Pokemon and finish crossing the aisle or street to get out of the way. Again, in Walmart, no one cares as long as you are not blocking the aisle.
3. Do not "freak the mundanes". Walking or riding slowly along as you catch the Pokemon avoids you sitting in front of someones house holding a phone. Avoid loitering and choose your locations for lures carefully. Gyms require a bit more time there, but most of those are public places. Be aware of where you are and what else is occurring there. Be sensitive to what they will be doing the rest of the time. Many historical sites love the attention. However, if players are not sensitive, many establishments will request to have their pokestops or gyms removed, and that will lessen your opportunities for gameplay.
4. And do I even have to say - don't play and drive....If you have to Pokemon Go - stop. (And not in the middle of the road.)
By maintaining an awareness of the world around you and playing sensitively, you can continue to make it a positive experience wherever you are and allow the game to continue in a positive light.