Manufactured logs work great and burn at a predictable rate. For a great waterproof firestarter cut newspaper in 3" strips. Roll the strip snugly and tie with twine. Make fatter ones by overlapping the strip with an additional strip/strips a few inches before getting to the end. Soak the rolled up starters in melted paraffin for a few minutes then hang to cool. Around the diameter of a standard magic marker works well.