I pull a bunch of leaves off their stems (enough to fill a pint jar, but you could use less), then either bruise them using a mortar and pestle and add them to the alcohol, or add both to the blender and whirr a bit. The mortar and pestle makes the final product clearer, but the blender is a lot less work. You only need enough booze to cover the leaves in the jar (it won't be quite full, because the bruising process makes the leaves smaller). I use cheap vodka, but any strong alcohol without a lot of flavor would do - the alcohol is more effective than water at pulling the sweet chemical out of the leaves, and it also preserves the extract. I let it sit for about a week, then use a cheesecloth to remove the leaves and squeeze all the liquid from them. If I used the blender, some tiny leaf bits will pass through the cheesecloth and settle at the bottom of the jar, they don't hurt anything other than looking weird. Then I just keep the jar in my kitchen to use as needed. I add about a teaspoon of it to my half-gallon tea pitcher or for a cup of tea, I just kinda dip the spoon in and then stir my tea with it - it's strong stuff, so it's easy to use too much.
