I/L wizard advice plz?

I'd go cold beam first, then when you hit 3rd job you can add slow. After all, the main uses as far as slowing bosses don't happen til later on into 3rd job/early 4th job anyway. As a training feature, your Ice attacks will do the job until then. So I would make sure you Max Amp, Ice Strike, Booster, Seal, and Partial Resistance first. Though you could just get one point in Partial Resistance and then throw the other points elsewhere if you'd like.

Anyway, The main reason for doing this, is that Thunderspear and Comp Arrow aren't all that great. Thunderspear gets replaced with Chain Lightning and Comp arrow sucks if you ever end up using an Elemental weapon, and even if you don't, it's replaced on most monsters with Chain Lightning as well. Cold Beam, on the other hand, can come in handy once you start your Ice Strike training for taking out a stray monster. Yes, you could use Ice Strike to do the same thing, but there are times you don't want to have such a far reaching area attack or times when you don't want quite as slow of an attack, pre booster levels. If you max all the skills I suggested above, and leave out Comp and Thunderspear, by the end of the 3rd job you should have 31 extra points, more than enough to max out slow and get some points in any other skills you want to have for fun.