for a fire sorc i reccomend having ts as a secondary skill
skills will be approx:
5 warmth
20 lightmastery 20 thunderstorm
20 hydra 20 fire mastery
1 to all requisites
thats 100 skills thats
attainable (with quests)
at level 89 i'd be maxing lightmastery/thunderstorm as your last skills

depends if you want to be dr..
i'll suppose you do
i reccomend using
wizspike (with um, or ko rune, or 15 all jewel with 9 str/dex)
shaftstop (with shael)
stormshield (15 all resist, -15% requirement)
shako (with shael)
thundergods vigor (or trangs depending on preferences)
ravenfrost ring
stone of jordan
+65 hp waterwalks (5%+max fire resist helps sorc v sorc btw)
+3 fire skills /100 hp amulet

lidwall/oculus for casting ts (socket doesn't matter)

10X fire skill charms of _____ (life/sustenance/balance/vita/dex/str)

10Xlit skill charm no suffix for casting ts/energy shield

10X resist (depending on which jewels you use in gear)
small charm of vita
the best would be
serpents small charms of vita (with 10, thats 170 mana 200 hp)