This is probably a rather silly question, do i go through every subject doing level 1 and then start from the first one again to do the next level or is it better to go through the levels one subject at a time?
I think it depends on what suits you the best.
I have tried several methods and what helps me most if I do a short section of, say, 10 skills to level 1 and then go back to complete to level 2. Then start the next short section to level 1 then back to the first section to level 3 then the second section to level 2 etc etc etc.
That way I dont get too bored and I still make rapid progress down the tree! But hey, I can always change it if it stops motivating me.