The search string that we constructed looked like the following:

-inurl:htm -inurl:html “index of mp3 “Oct-2005″ “Fresh Fantasy Dizzy Singers

There are more filetypes that we should exclude from our searches to get better results, those are:

php, asp, doc, pdf, shtml and txt

You may want to add additional file types and extensions. Just add -inurl:extension to your search query to exclude them from search.

To exclude these as well we use the following search string:

-inurl:htm -inurl:html -inurl:php -inurl:asp -inurl:doc -inurl:pdf -inurl:shtml -inurl:txt “index of mp3 “Oct-2005″ “Fresh Fantasy Dizzy Singers

We also don´t want the following results to appear in our search results:

ringtones, lyric and playlists

That means we exclude those as well and get:

-inurl:htm -inurl:html -inurl:php -inurl:asp -inurl:doc -inurl:pdf -inurl:shtml -inurl:txt “index of mp3 -ringtone -lyric -playlist “Oct-2005″ “Fresh Fantasy Dizzy Singers/code>

You can again add keywords that you do not want to see in your search results. Just use the -keyword parameter for that.

The last step is to add more possibly words that appear in the directory structure, those are

"parent of" and "last modified"

Our final searchstring now looks like this:

-inurl:htm -inurl:html -inurl:php -inurl:asp -inurl:doc -inurl:pdf -inurl:shtml -inurl:txt AND (“index of|"last modified"|"parent of") AND mp3 -ringtone -lyric -playlist AND “Oct-2005″ AND “dizzy singers

You can of course exclude more search types from your searches, this depends on the circumstances, maybe you don´t want audiobooks to be displayed, or only audiobooks..
I think you have the basic understanding now to enhance the searches yourself and get pretty good results using google.