In 600ml beakers I use 50/50 vinegar/water to start with a few drops of dish soap, then cold water with a few shakes of langostina pot cleaner, cold water with 1/2 teaspoon of baking powder, hot water, then final rinse with cold or distilled water.
You get really shiny brass this way, inside and out. The 6mmbr link is good. I basically use their recipe and went from there.