I would leave off the misting, it has been suggested it can stress a dragon, bathing is a much better option.
When you say watery, do you mean a gel like casing to the poo? Only that is a good sign that your dragon is well hydrated.
Best substrate in my opinion is paper towel, again particularly in young dragons, it's easier to clean and doesnt harbour bacteria in the same way particle substrate can.
Good staple greens are cress, butternut squash, spring greens and peppers.
Make sure your temps are correct, for younger dragons that basking spot needs to be 115* or higher. Temperatures are imperative for good digestion.
Once you've got the set up right you will have a healthy happy dragon