Do you watch any bottle diggers on YouTube? That rapidly accelerated my knowledge of all things dump digging, along with perusing this and other bottle sites.
Do you have a cemetery dating back to the 1800's in your town? Does that cemetery have woods next to it, and better yet, a creek running through it? That's one of my go to spots if I have a limited amount of time in an unfamiliar city. Your mileage may vary.
If you check out some YouTubers, I recommend Digger Dave Beeler, Southern Searcher, and Adventure Archaeology. Just between the three they probably have a combined century of knowledge and they freely share a lot of it with viewers.
Is there a local bottle book for your area? Seek it out, study it. Chances are it'll be hard to find, out of print, and a little pricey, like the one I have for my area. Probably still a worthwhile purchase though, along with other books you can get your hands on.
Do you have a probe? Do you know any local collectors who might show you a long picked over dump they swear was dug out in the 60's? I don't believe in dug out in the 60's. There's still millions of bottles in the ground. You'll find some nice honey holes. Good luck!