It depends on the chemical, as some are more stable than others. For what I have dealt with, I just keep them in a dark place in an airtight bag. Don't know how good that is, but from what I hear it is what most people do.
Phenethylamines are in general more stable than tryptamines. Therefore proper storage is more necessary for most tryptamines. Meretrix is right, an airtight bag is always a good idea. I would suggest storing them in the freezer with a dessicant to absorb any extra moisture that might get in. Some compounds are really difficult to store, for example CP55940 - which can only be stored at -20 degrees celcius according to most reports.
For powders... In a wrap, in a tupperware box, in the fridge is pretty good. For liquids... In a dropper bottle, in the fridge is good.
Also would like to note that I have heard many many times that keeping them in a powder is much better than turning putting them into a liquid. I have heard they stay much longer without any degrading in powder form.
I don't understand what the reasoning is behind liquids anyway. It's not like diamond/mg scales are expensive or hard to find. Some RC sites are even starting to stock them....
^because kids are lazy (and MOSTLY broke) and don't want to spend another 80$ dollars on a scale after the what the RC costs AND then the extra money to get a money order etc etc. converting them into liquid is at least a little better than just straight up eye balling it.
