US headline style: Quoting conventions within the US vary according to personal preference or corporate style. But the usual "headline style" rule is that the following should not be capitalized except at the beginning or end of a title:
* articles (a, an, the)
* prepositions (depending on length; the four-letter rule seems most common)
* coordinate conjunctions (and, but, or, for, nor)
* "to" as part of an infinitive ("to be")

Beware of "prepositions" which actually function as other parts of speech, typically adverbs or adjectives: "Carry On the Fight"--here, "on" is an adverb, inseparable from the verb and taking no object; "Up the Down Staircase"--"up" serves as a preposition, but "down" serves as an adjective. Also note: "Lovely as the Dawn" (preposition), "Twice As Nice" (adverb), "Do As I Do" (subordinate conjunction), "Fools Such As We" (pronoun).

If the title contains an embedded quotation, the quote should be rendered in "sentence style", even if it represents a title.

Different organizations follow different conventions regarding compound prepositions, hyphenated words and the like. And there are a few other title gotchas in headline style, but they rarely occur in song titles: "The Ballad of E. coli", "Baby, Balance My pH"...

Other styles: With Internet illiteracy, there is an increasing tendency to use an initial capital on every word, or (gak!) to use all caps. But capitalization rules exists for reading clarity; these trends make text less readable and should be avoided.

With "sentence style" (initial cap, normal cap rules apply thereafter), you have none of the inconsistencies or quandaries inherent in headline style, and no special rules to remember--which is perhaps why most of Europe and South America follow it. It is also the most readable and least intrusive style.

Headline style and sentence style are sometimes used together to distinguish "descriptive" song titles ("The Barkeeper's Widget") from first lines or titles derived from first lines ("As I surfed the interwebs").

Non-English styles: In German, one capitalizes all nouns and some pronouns as well, whether in titles or in normal writing. In other words, German uses sentence style, appearances to the contrary.

When citing the title of foreign songs, one should attempt to conform to the conventions of that nation or language, but this rule is often broken, particularly in indices and listings. Translated titles follow the conventions of the new language. Transliterated titles follow the conventions of the source language--presuming their writing system supports capitalization; otherwise I advise using sentence style (you need only recognize proper names).

Spacing before punctuation: I've studied many languages, and from what I've seen, it is not common to include spaces immediately within quote marks or before punctuation at the end of a sentence or clause--at least in modern usage.

Quote characters are also locale-specific, so folks may want to mention the most prevalent set of quotes used in their country. Angle quotes are common in French and Russian, though double or single quotes are also used. Some languages use (or once used) opening quotes aligned with the baseline, and even reversed.

A different quoting convention (such as a long dash) may be used to denote speech.