Check out A Correct “Only” by rogersgeorge. Here is an excerpt:
People commonly put “only” at the beginning of a clause when the word actually modifies a word within the clause (for example, in the first panel below). The rule is that adjectives (such as “only”) modify the word following. Putting that “only” too early can lead to nonsense.
On the second…
The full article is available here.
