One main factor is the rings you have access to. If you've purchased good rings for either one, go for that. I personally like fire mage at lower levels since cloak of fire is actually effective and avery low energy costing skill. Ice mage is great if you have the rings, as you can literally one or two shot enemies. I'd recommend giving both a shot.
As for skill builds, for ice I would do max shards and attune, put as many points in eshield/sac/lure as you want then rest into ice blast.
For fire I would max fire bolt, fire attune and cloak of fire, then put some points in eshield/sac/lure and the rest into fire storm.
Incinerate and frostbite aren't that great, and only serve as extra DPS if you have the skills points (which you don't have at low levels).
Freeze is good for ice mage build if you die pretty often, as it lets you survive during skill cool downs.
Finally agreeing with me on inc and frostbite :p
Well it really depends on ur budget, low lvl would have low budget, but this one is an alt, so it really depends.
If u have low budget, go with armo's suggestion or bobert's suggestions all over the last threads
If u have high enough budget, go full dps, either fire or ice (ice would nuke on low lvls but i prefer fire)
If full dps fire :
firebolt - maxed
firestorm - maxed
fire attune - maxed
fire lure - half maxed or a bit more (maxed for bosses unless u got more mages)
rest in sac/e.boost/e.shield/cloak/inc/ice shards (if full dps, i say go with ice shards, great skill, and use lure of ice at lvl 1, my lvl 82 has all skills maxed, fire over half, ice shards maxed +2 pts, and sac at 3, so its possible to make it effective with the right gear)
for full dps ice :
pretty much the opposite
ice shards, blast, attune - maxed
lure - half maxed or a bit more
rest in firebolt (firebolt is even better as an extra, and fire lure at lvl 1) or the rest of the skills mentioned (just not cloak, and frostbite instead of inc)
Thats only for full dps , and its very costly to use, energy and health issues unless ur using sacrifice/e.shield, strong sacrifice should help a lot with energy issues, and same for e.shield and health issues, the problem is that both this skills affect other things, e.shield will take a lot of energy, and sac a lot of health, theres e.boost but i really prefer sacrifice, and before using either one of them, think what is a bigger issue for u, health or energy?
Other than full dps, again what armo suggested is great (cloak is really good for low lvl saving), or u can look at bobert's posts, he started a new mage, with no plat items, making it possible to lvl without so many issues as a low lvl, if i wasnt lazy i would try it myself.