After a post I made and when Ryuujin27 brought it to my attention, I thought it was worth its own topic.

How would you approach a local and what would you speak about to start a conversation?

In my case, my most successful moments were when I was asking for help/directions. It gives a legitimate reason to talk to someone, and might even turn into a normal conversation.

Basically anything small to demonstrate that you rock at JP - nothing dorky, but just show them that you can speak well and understand well and are a nice dude(ette). They're often amazed and that alone becomes the basis for a pleasant conversation.

If you're not there yet, just keep working until you are; you will have loads of fun.

Just approach them the way you would approach any other stranger you want to talk to, using English or Japanese. Just don't make it seem like you only want to speak to them because they are Japanese, and don't go on and on about how much you love Japanese culture because they'll think that you are creepy/otaku.

You don't want a language partner, because they are useless and a waste of time. You want FRIENDS.

Same way you would approach anyone. Better just frequenting a place a lot and meeting locals that way. Thats how I am going to do it. Find a bar with cool people, frequent until friends are made. And somehow resist becomming an alcoholic in the process.

Not exactly what you were asking, but still useful: when going into a restaurant or approaching the counter at a store, always say こんにちは (or whatever is appropriate). It doesn't just mean hello, it also means "Hey, despite being a foreigner, I can speak Japanese. And look, my accent's pretty good too!" That will make the encounter go much more smoothly.

As far as talking with locals, I haven't done it much. Once was in an izakaya, by myself. I waited until a table of old guys started talking about me, then joined in the conversation. I got to learn all about the cultural significance of whaling, and about the hangover you get from your third 焼酎. But it's kind of a passive/hoping method, and shouldn't be counted upon.

Hangover from only 3 shochu? Weakling

My plan is to find a intimate place I like near where I'm going to live and to then become a "regular". My very first night in Tokyo I walked into a bar in the Golden Gai that had all of about 7 seats in it and I ended up meeting all kinds of people wanting to talk to me. Three groups of people that I met there that night ended up taking me out to other places during the rest of the week and that was when I had zero Japanese ability.

Comfortable place to talk = talking comfortably.