The first step in making brandied cherries is to change your clothes. No seriously. You've got to pit your cherries, and pitting cherries is a juicy mess of an endeavor, so go ahead and put on whatever you'd normally reserve for yard work or something. Pitting is an absolute necessity, not only because it makes eating them easier, but because it allows much more of your spicy brandy concoction to soak into the cherries. You might not own a cherry pitter, but they're not too hard to find, and not that expensive. I got mine at a restaurant supply store for ~$5. It looks not wholly unlike a primitive torture device:
Now I'm not going to sugar coat things, here--pitting isn't fun. But you must persevere, so flip on the telly or a podcast or whatever and get to work!
When you're finished, set the cherries aside, and raid your spice cabinet. Be sure to grab some cinnamon, cloves, and cardamom--whole sticks/pods are preferable, but ground is OK too. Other spices in that general family can also be good, like allspice or maybe even a teensy bit of coriander.
Add equal parts white sugar and water to a large saucepan, about a cup of each per pint of cherries you have. Add your spices, remembering that a little goes a long way, especially when it comes to cloves (and cardamom). And you know what else? It certainly wouldn't kill you to add a splash of vanilla extract to the mix. Heat it all and stir until the sugar is dissolved, and then let it simmer for around 5 min. While you're waiting, you may as well go ahead and open your bottle of brandy. And while your bottle of brandy is open, you might as well pour yourself a little glass. I mean, what else would you do with 5 minutes?
After making sure that the brandy hasn't been poisoned (nobody wants poisoned brandied cherries!), turn off the heat and dump your cherries into the pot. Stir in some brandy, maybe 1/2 cup per cup of water you put in, but no one's complaining if you round up, you know what I mean? Cover the pot and let everything sit until it's cooled to room temp, and then transfer cherries and syrup to a sealable jar.