How much of the sample should I use?

A very small sample is sufficient. In general, your sample should be about this size: ( ● )

Unless otherwise indicated, use the following guidelines:
Pill: Scrape off about 5% of the pill.
Powder: Use a few grains, about the size of a pinhead.
Paper: Cut off a small corner.
Liquid: Place a couple of drops on a small piece of uncoated paper.