hey, folks!... there's a global difference you seem to be ignoring... and, yes, there are 'laws'... where british usage calls for single, the american rule is double... and v/v...
american punctuation rule is double for quotations and dialog, with single for interior quotes... use of single quotation mark is not correct usage in american writing for anything other than that... if it's not around an interior quote, it's an apostrophe...
if you want to be taken seriously by agents and editors, you'd better follow the standards of the region... don't, and you'll be seen as an amateur [or worse]...
every professsional writer i've every known keeps a punctuation guide right next to their strunk and white, a dictionary, and roget's... so, for a beginner to not do so, is just plain silly...
there are two good punctuation guides on a 'tools of the trade' list i send to those i mentor... email me if you'd like me to forward it to you...
love and hugs, maia
maia3maia@hotmail.com