I never start doing anything in Sonar until I have chords and melody mostly worked out. I think a big part of the reason so many folks have 1000 half finished songs is because it's so easy these days to put the cart before the horse when it comes to recording. Your creative songwriting gets buried by your creative recording. You end up with a bunch of well produced, guitar layered, vocal harmonized, chorused, flanged, sufflayed and delayed, but unfinished songs.
Better IMO to have the song mostly worked out before going to the DAW. THen, once you are ready to begin recording, work fast. Get your ideas in place and work quickly, without worrying too much about setting levels or getting the best tones or performances. Just get your ideas fixed in Sonar.
At this point you can finally hear your song as a whole and finish your songwriting decisions: should the intro be shorter? Should there be two verses before the first chorus or only one? Should the solo be eight bars or only four? Working quickly like this frees you up to start pushing things around, copying and pasting sections, shortening or lenghtening things until the song is right without haveing to worry that you are ruining that "perfect take" or "voodoo tone" or "awesome production" that you spent 3 hours working on. It enables you to make the best decisions for the song, without being strangled or swayed by production decisions.
Only once the song is written should you start recording keeper tracks, becuase at this point you are free to make creative production decisions without having to worry about songwriting decisions.
I know loops make certain things easy and a lot of folks like to use them, but in general it's pretty easy to tell when songs have been written around loops. I say, write your song first.... then record it.
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