I've read the rule which states:
One ought to put an adverb of manner after the main verb if the verb is intransitive, but if there's a direct object after the main verb and the verb is transitive you can put that adverb either in front of the main verb or after the direct object.
Following that rule, I've made up these sentences with the adverb of manner "well":
1) I sing songs well. / I well sing songs.
2) I play football well / I well play football.
But I'm not sure if they're all actually correct. Could you explain the right rule to me?