Weed grinders are fairly simple tools and are easy to use. The following instructions are for your average 4 piece grinder like the one below.
Step 1. Remove the lid (1) of the uppermost section and place your buds onto the teeth (2) in a circle midway between the center and outer edge. Placing your bud in the very center tends not to work as well.
Step 2. Rotate the lid (1) repeatedly to grind the buds giving it about 5 good turns in each direction. Then, peak under the lid (1) to make sure all the buds have make it through to the next section. If not, give it a few more turns in each direction and check again.
Step 3. Before opening the grinder, give it a little sideways shake to even out the ground up buds so they don’t spill out when you open it. This also helps more kief fall into the kief catcher at the bottom.
Step 4. Unscrew the main compartment (2) and enjoy the perfectly ground buds.
Step 5. After a few uses, kief will collect in the bottom most compartment (4) and it may be collected by unscrewing the screen section (3).