There are lots of ways to cut bottles, I’ve tried all of them that I can find and think of, my favorite is still the tile saw. There are pro’s and con’s to using a tile saw, it’s a tool that is great for somethings, not so much for others.
Things to consider:
I have an 10″ tile saw, so I roll the bottle into the saw blade as I cut. If you have a larger saw, you can pull the blade through the bottle, I still recommend a slight roll, it will keep your cut smooth and keep the last little bit from breaking.
Once you get the neck and the bottom cut from the bottle, you’ll have a cylinder of glass that is the start point for lots of other projects.