I agree with your closing comments, but I think it's useful to make the distinction that it's helpful to begin with predictions that are very clearly successful or unsuccessful, even if this might be construed as erring toward more 'objective' metrics. This is why I chose #13 to begin forming my predicting habit; my paraphrases of others' positions are usually easily categorized as either correct or incorrect and salient outcomes are better for habit formation.

Great post!