First, I establish the important areas and make a small path just outside them. For me the important areas are building like Town Hall, the Roost, Train Station, ReTail, Town Plaza and the Police Station (assuming you have built that and the Roost).
Next I start seeing where my buildings lines up and make paths to connect then as straight as I can. Sometimes I have to get crafty and make a path go one way to avoid being broken by a pond or rock. I typically keep my paths 2 wide, except if I'm making the path go up to an entrance like the Town Plaza. Since the tree is 3 spaces long, I make my path coming up to it 3 spaces wide. Same with other entrances.
Once you have a path to the important buildings, I then start wandering around town, seeing which areas I can put pathing down that I frequently travel around and will make for the easiest traffic. I use the bridges as a reference, because I often put my bridges in high traffic areas and for convenience, making getting to building easy without walking all over town. So right now you would make paths from bridges to the buildings and anythin else you want to connect. Maybe you have a large area full of nothing? Make a pretty walk way, the wisteria trellis makes a wonderful walkway scenery if your path is 1 or 3 wide. Have an even larger area? Put a path around a fountain or statue fountain to make it like a mini plaza. I often see inspiration on tumblr and twitter of how people landscaped. I used Pinterest as well, but keep in mind it's all reposted stuff without credit.
Now establish, do you want direct paths leading to your animal houses, the beach ramp or your villagers houses? I often don't do this and will either have them all live in one area or have a dirt path that leads around town to those areas, but never directly at their door.
Fine tune the path now, make curves where you need. Maybe that path works better if you have don't have it directly lead to the doors of buildings, and instead it's on the cobblestone or just outside, but enough to make a path to it.
Pathing requires alot of work but when you're all done, man is it worth it to walk around town surrounded by beautiful scenery you created. If toy need help or need to see what I wanted on about, I can invite you over to Moriyo Village, where I used this method to create my paths.