Finely julienne the ginger. If the skin bothers you peel it off first. Slicing the ginger is fine too, but if you julienne it more juice will come out easily.

If you are going to use it all up right away you're done. Just make sure that the ginger doesn't poke up above the syrup (to prevent it from molding).

If you want to keep it for a while, after plenty of ginger juices have been exuded, heat up the syrup to disinfect it. If you do this it's a good idea to have the mixture in a heatproof container to begin with.

You can transfer it to a pan and heat it through that way too.

You can leave the ginger in the syrup, or take it out. If you are taking it out, it's easier to do so when the syrup is hot and not so sticky.

The amount of juice that comes out depends on the ginger, but if you use the amounts indicated in this recipe you should end up with a light syrup which won't solidify easily even when refrigerated and is easy to use.

If you prefer a thick syrup, reduce the amount of ginger, or reduce the syrup a little by heating it. The syrup in the top photo uses a bit less ginger.

Easy version: Use whatever amount of ginger you like, and enough brown sugar to bury the ginger. You can make it in the same way as above. (It's easy, but less likely to re-crystallize.)

The flavor will change depending on the ratio of ginger to brown sugar. You can use the ratio you like, but if there's too much brown sugar it is more likely to crystallize.