heres what I did, and what most people are going to recommend.
1st Sp into iron arrow
Get mastery to 10ish
Then get soul arrow to 2 or 3, and booster to 6 or 7
then put mastery to 19
I got iron arrow to about 25 then I maxed Pkb.
Then put mastery to 20
and then(if you put 9 into focus during 1st job) max focus.