I have learned Dvorak by taking a week off during the summer (I was a student back then, great for doing things like that) and spending an hour or two each day through a touch typing course. In my case, I used gtypist, because I'm a GNU/Linux guy, but I think there are better ones out there.

My two reasons for learning dvorak was my rather poor touch typing form on QWERTY and the arguably superior layout for general English text.

Dvorak however is not a panacea -- while I can type english text rather well, I'm still very poor with my right pinky which has an immense amount of work if I do programming; all of the following characters

-=/+?[]{}_

should be handled by a right pinky in dvorak layout. []{} are especially far away for me on almost any keyboard and I still fail to type them efficiently.

Also note that many people argue that the ergonomic advantages of Dvorak are purely subjective and unverified. Learning to touch type on QWERTY properly might be a good subtitute for learning Dvorak.

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My personal tip is not to rush any touch typing training and when you feel your brain struggle (it also caused me a headache the first day) just take a break. Also the retraining of the brain produced some very vivid dreams in the first two nights.