L7 is a must whatever build you go
Get strike at 5 during first job, then all gun skills available to you.
Then get powershot rightaway (i put off grinding for a day to conentrate on my TM because at this point TM is harder to lvl).
After that it's either spree or L7. I'd get Spree first tho, since it'll help you more and L7 has pre reqs. Unless you plan on pvping early on (?!?)
Booster and powershot is mastered. Spree and L7 idk yet, but L7 most likely specially if you go scientist since aura of luck is unavailable to you and you WILL need all the luck you can get.
Then move on to DS, etc etc. Only til 100, right? Getting all those skills will keep you occupied enough to put off worrying about later;o
zzzz o and look in sense type guides for more in depth help;o