Beef shin will work better than braising steak - the latter tends to be too lean and therefore can end up being dry, even when slow cooked.
How I make mine:
Cut beef into large-ish cubes, and brown in a frying pan. (You may need to do this in batches, to enable them to fry/brown, rather than just steam, which is what will happen if the pan is over-crowded. Season with salt, pepper and whatever herbs/spices you want to use. (I generally use dry oregano, a bit of dried cumin and sometimes a small amount of chilli)
When nicely browned all over add the meat to your slow cooker. Then in the same pan (don't discard any of the fat), brown some chopped onions, carrots and celery. Season. Add that to your meat.
Then deglaze the pan with some red wine, or cider, or beer - whichever you have to hand/prefer! Add that to the slow cooker, stir it all and then leave it. You don't need much liquid, as there will be plenty from the ingredients.
Occasionally I'll also add mushrooms, but don't do this till towards the end of the cooking.