First all, the Holy Grail of walking a dog, especially a big one: loose leash walking. I'm happy to say that, combined with the clicker, repetition and improved consistency (I've never said I was perfect; I just play it on the Internet), Elka walks loose leash very well. I still Heel her on my right. We're also working on the left, for which I use the cue "Fuss", which is German for "heel", so we can act all fancy.
We've also worked on reactions to two persistently present things: barking dogs, and machinery, be it from construction or from yard work.