Okay, I'm REALLY into absinthe, and you have to drink it proper for the good stuff. And, all due respect to your Serbian friend, the Czech stuff is complete shit. Find American or French and you're off to a good start. It should be entirely organic ingredients, as in only herbs that should be listed.
What you need now to get this good is sugar and very cold water. Sugar cubes are ideal, but not required.
-Fill your glass one fifth to one third absinthe. I think a fifth or a fourth is the perfect balance, but hey, different strokes.
-If you have sugar cubes, take a fork and place it across the glass with the sugar cube resting on top. Drip the cold water onto the cube until it's saturated, then slowly add more until the sugar is totally in the glass and then fill the rest with the water. Drop from as high as possible without it splashing out.
-Without a cube, put the amount of sugar in you like. Estimate one cube, but this is taste preference. There should be a sweetness, but not overpoweringly. There should be a spice behind the absinthe's flavor that will be offset with too much sugar. Then add your water from above as to blend the sugar, water, and absinthe.
You'll notice the liquid goes from a translucent, brilliant neon green to an opague, milky white/green color. You'll also notice the aroma come out fully at this point. Sip and enjoy.
AH GOOD. I WORKED ALL DAY, I'M NOT IN BOSTON, AND NOW I'M DRUNK AT HOME AND WRITING ABSINTHE PREP INSTRUCTIONS. WHAT A GREAT WEEKEND I'M HAVING NOT IN BOSTON.