I figure "right of way" goes like...
1. Walkers
2. Runners
3. Cyclists
4. People with dogs
I fit into the first three on various occasions. I figure if I'm walking, pretty much everyone else can see me, and avoid me. I'm moving slowly. I try to keep to the right side of trails when possible.
When running, I look out for walkers. I yield to them and use my speed to dodge obstacles before they arrive at them.
When I'm cycling, I stay on the lookout for pretty much everyone. No ripping blind corners (how the hell is a walker or runner supposed to yield to a mountain bike ripping a blind bend at 30km/h?) and hopping off when necessary. I use my bell, but assume no one hears it. Safest that way.
People with dogs just need to be on the lookout for everyone. The let their damn dogs walk parallel to them, essentially making a wide trail block with the leash. Thanks for that! They let them crap all over everywhere. Our urban trails are leash-on by law, but most let them loose, and thanks for that too, as when I run or bike, having your dog chase me IS the highlight of my day. Why do you take offense to me kicking your damn dog, you chose to let them off the leash?