Over the last week, I've been working hard to maximize my matches. Right now I've matched virtually every song I have that's available on the iTunes Store. Here's my workflow:
1) Make sure the song CAN be matched. Some of my albums (for example, Tool's Lateralus) are not available on the iTunes Store, and I would be wasting my time trying to match them. Instead, I've re-ripped them in AAC (256k) format, and made sure they were appropriately tagged before letting them go in the cloud.
2) Compare the song duration with the one listed on the iTunes Store. This is where most of my progress was made: one of the key element that's checked when matching is the song duration, and if it doesn't match to the second, the song gets uploaded instead.
The workaround here is to tag the right length (Right click > Get Info > Options > Stop Time) and to create an AAC version, then delete both the old and new version from iTunes and iCloud and reimport the new length-adjusted version and try to match it. Sometimes, the length seems right but when you look at the "Stop Time" field the song is a couple of milliseconds too long; try to round off the excess length to see if it works.
I was even able to match songs that are on one track on my album but on two tracks on the iTunes Store (for example, The Offspring's Pay The Man / Pretty Fly (Reprise)) by cutting the first half to the right length and matching it and selecting the right portion of the second half and matching it too.
3) If nothing works, try downloading some other version of the song (I guess the legality of it may depend on where you're from, but morally you already paid for the song and you're only trying to match it). I had several tracks of my Queen's Greatest Hits II that would not match event if I cut them to the appropriate length, and I was able to match them by using songs downloaded from a torrent.
Unfortunately, most of the torrents available are CD rips; only on rare occasions have I found iTunes versions of the songs I tried to match.
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The only things I haven't been able to match thus far are shorter versions of a song (I don't know why Damien Rice's Eskimo is longer on the iTunes Store, but I can't get it to match) or songs that are split on my album but on one track on the iTunes Store (I tried to join The Mars Volta's epic Cassandra Gemini and match it, and even though it had the right length, it wouldn't match).
The one thing in KNOW, however, is that although accurate tagging might help speeding up the matching process, it is by no means essential. I had no matching success by simply tagging my songs exactly as the iTunes Store does, even though they were the right songs; the only thing that worked for me was changing the song LENGTH to match the one found on the iTunes Store.
Hope this helps!
