But don't forget, some of those songs that have weird internal sections, if you start them in a 'black' key (Don Imus, where are you now?! ), the odd section might be in 'C', or another easy key....

And if you CAN now play those sections in the odd key they are in, well, that just goes to show you CAN play in those keys! Now just do it a bit more, and soon enough, you'll have another key under your belt.

I find the best way to learn anything new is repetition, without a change. So if, for instance, you say 'I can play in 'C', but 'Bb' gives me fits', try playing in Bb (and NOTHING else!) for a month. Not one single song in any other key. For a whole month.....

Yes, at first it will suck, but after a while, you'll go 'this isn't so bad' and at the end of the month you'll go 'why did I find this hard at all?'.....

12 keys, 12 months... Coincidence? I think NOT.......!
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An arranger is just a tool. What matters is what you build with it..!