^ Along with a scale you're going to want to use liquid measurement really.. Weigh up for example 20mg with your scale, then dissolve in 20ml of high proof food grade alcohol or another appropriate solution and you can measure 1ml with a syringe for a 1mg dose.
If you just use a scale, you'll find that milligram scales can sometimes be out by a few milligrams and while with many drugs that's not an issue, with Alprazolam that's the difference between just enough and way way way too much.