I use Formula 420 - glass, metal, ceramic, etc., cleaner. You just have to get the cleaner worked into every section and then shake it up real well. I always get them rinsed out real well with hot water before putting the cleaner in and then after, (of course, lol).
The alcohol and salt like jay said will work but, I found that they started leaving a bit of a white film that I didn't like so I stopped doing it that way. I thought I'd save some money going that way but, it didn't last long. It definitely works though if you're out of the other but, I wouldn't like it long term myself.
You can get some pretty good deals on like 3 and 4-packs of the bottles of 420 on Amazon.
One thing that will really help you is with any pieces that you're using on a regular basis to just rinse them out every day or two, depending on usage, with hot water. If you stay on top of them like that you won't even have to use the cleaner very often.
I had almost all of that written out last night but, I passed out in front of the screen. :facepalm: lmao