I'm using a soft gum brush which is included in Earth's Best toothpaste pack. Yup, it's all natural and doesn't contain flouride but cares for my baby's first teeth up to 3 years of age I believe. Schuyler's also having fun with the its strawberry and banana flavor!
Used a soft cloth alongside a low-flouride toothpaste for my sons before. Good thing we have the organic ones these days.