First priority should be getting enough AGI and STR for equipment and then putting rest into ENE. Once you reach lvl 280, you wont need anymore AGI but you will need more STR later on once you finish all ENE skills!
DO NOT max the last 2 skills on the first row, they are for PVE!
Focus ENE skills until you are lvl 400 or 500
I HAVE PURCHUSED 2 ADDITIONAL SKILL CORES (unlock at lv600)
T3 - Vicious (dead hit and stun res) (Charon accessories without core)
T4 - Starfall (dead hit and stun res) (Holio accessories without core)
T5 - Haion (Hekaton accessories)
T6 - Unnamed (Wuldor accessories)
T7 - Sun (NO CORE)
T7 - Shining (WITH CORE)
Mainly focus on what increases DIRECT SKILL DMG %
For T1 and T2 you can use ENE and STR runes
For T3+ only use ENE
Here are some build guides from the Top ENE DLs
Dm eden.67 if u want more info on something (PLEASE just ask the question instead of saying "hey")