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jason o.

tab and by ear, or by memory of hearing a riff/song, then I try to work it out without listenting to it

Eet Fuk

In my opinion, the third method is the best way - altough it is the most difficult and time consuming as well too. If you keep on trying hard searching for the right notes, you possibly discover a lot of great things and techniques, which will be quite useful in the future. Don't be lazy kids!  

Zealmet

I use the third method, but to tell the truth, sometimes after long time of selection, I feel that I selected notes wrongly, and then I check the net for tabs. Though, usually I'm not satisfied by the many variants in the net too (if I can't find original tabs by the author), and then I take one and join it with my variant and get something worthwhile.