Spears skills I use are Chain Tiger, Ghost Petal and that other one where you take a big sweep of your spear and smack something real hard... can't remember it's name atm.

And also the dragon throwing spear one.
As for Ice skills, obviously Ice-Jade Force, ice shield, nuke. I have 1 point in Arrest for drawing mobs out of crowds, though I can do the same with the nuke now that I have it.
And Force skills I have are Heal Other, Harmony Circle, Revive, and 9 levels of the poison cure skill, which I plan to stop leveling now because it'll hardly get any more useful than it already is.
For all 3 of the skill trees, I make sure to increase the very last skills (hp up, mp up and defense up) every 10 levels.
I keep all Masteries at least 4 levels below my character level. So I gain enough sp per level to raise all skills, and then raise the Masteries when I levelup and do the same thing again. The only skill I don't have constantly maxed is the poison cure, and that's because I stopped bothering with it. x)
And finally... my character build was 1str:2int untill level 24, but pure int since then.
Did I miss anything...? Ohh, ya. I missed giving some random useful tip, didn't I?

Well okay then. Did you know that fire/ice/lightning nukes do even more damage if you use the weapon imbue skill first? It's not a significant increase, but definitely noticeable.