A practical english grammar - Vyssaja skola 1978
Adverbs modifying special elements in the sentence
Sound symbols
When only modifies the subject of a sentence, it precedes that element.
Only John knew the answer.
When only modifies some other element that occurs before the main verb, it precedes that element and the subject and verb are reversed. This usage is formal and literary.
Only by hard work could he succeed.
Only to a brave man will that award be given.
If only modifies the verb or some element following tne verb, its normal place is medial position, except that puristic usage insists that it must be put next to the element that it logically restricts.
He could only succeed by hard work.
He could succeed only by hard work.
That award will only be given to a brave man.
That award will be given only to a brave man.
Too may follow the subject, if it modifies that element specifically; or, it may follow the verb (and its complements, if any), regardless of which element in the sentence it modifies. In speech, it is easy to indicate which, since that element is stressed. In writing, special type (usually italicizing the word) must be resorted to in case of ambiguity.
Mary, too, talked about him. (This arrangement is unambiguous; too modifies Mary.)
Mary talked about him too. (With stress on Mary, this sentence means the same as the one above.)
Mary talked about him too. (Mary thought about him; in addition, she talked about him.)
Mary talked about him too. (Mary talked to him; she also talked about him.)
Mary talked about him too. (Mary talked about several people; she talked about him also.)
Especially is an adverb that usually modifies (logically) either the subject or the object of a verb. When it modifies the subject, it follows, with pauses.
John, especially, should study this lesson.
When it modifies the object, it is in medial position.
John should especially study this lesson.
I especially dislike rainy days.
If especially precedes an adjective or adverb, it modifies that word.
It was especially hot that day.
The grass grows especially fast in spring.
For reasons of euphony, especially is not regularly used before adverbs ending in -ly.