Wizz Clerics are the better Wizzards imo (comparing to SubBards). Your Wizz Cleric is surviving more along with Bless and Rec. Div. and your ClericSkills are more useful at GW and FW then a Wizz Bard (Bards are only effective when they are two of them or even more).
+Max the Natural Spirit Line, and yes even Lightning if you have enough SP (OngFarmed or something).
+Max Force Mental Line (Life Control is not necessary so i wouldnt put any SP in it)
+Earth Mentalist
-Ground Charge is cool but got one big disadvantage, you gotta get very close to your enemy to use it so its not 100% necessary (i skilled it anyway)
-Root is cool and fun, but not 100% necessary, if you have the needed SP you can bug your enemy with it
-Earth Shock is very strong and useful: Skill it!
-Earth Barrier is sometimes a LifeSaver at Physical Mobs and there are lots of them so Skill it!
-Ground Rave > look Ground Charge!
-Mesh Root is the AoE of Root.
-Earth Quake is a very strong AoE so Skill it!
-Earth Fence same as Earth Barrier, skill it!
+Cold Mentalist
-Ice Bolt: Skill it!
-Mana Drain is very effective against Nukers which rely much on their Snow, after using it effective they aint able to recast Mana Pots, i loved to kill em with this skill, if you got the needed SP, skill it but its not working on mobs so not 100% necessary!
-Snow Wind: Ice AoE Attack > Skill it!
-Invisible is useful sometimes, if you are not ongfarmed, just skill few lvls of it.
-Frozen Spear: Skill it!
-Mana Drought is like Mana Drain but used on an Area: Skill it only if you got some Sp left.
-Blizzard: AoE Attack > Skill it!
-Crystal Invisible: Almost never needed, only for fun.
+Fire Mentalist
-Fire Bolt: Skill it!
-Fire Trap works on Mobs as well as on Players, its fun to use it at FW, GW but its not 100% necessary.
-Fire Blow is a multiple Fire Attack and useful at giants and Uniques, i would skill it!
-Detect is almost never needed!
-Meteor is the strongest Fire Attack and kinda useful so skill it
-Lava Trap is same like Fire Trap
-Salamander Blow same like Fire Blow
-Sprawl Detect > waste of SP
+Lightning Mentalist
-Lightning Bolt is a weak Lightning Attack and never useful but skill if you got the needed SP
-Lightning Shock is useful at Giants and FW, GW cause it puts Fear on your enemy and you can ran away or you got some time to repot, skill only if you got some Sp left
-Charge Wind knocks your enemy back, kinda weak attack, skill only if you got the needed Sp
-Teleport is kinda useless imo, the area you teleport is way to small, waste of Sp
-Chain Lightning is kinda useful at ongs but also not a strong attack, skill only if you got the needed SP
-Lightning Impact is AoE of Lightning Shock
-Charged Squall swallows lots of Mp, i wouldnt skill it
-Aerial Teleport is also useful imo, waste of Sp
Cleric Tree:
-Divine Creed: Skill only if you want to attack from time to time being a cleric.
+Cardinal Praise
-Trial Cross is not needed imo, dont skill it
-Healing is also not needed since its only targeting one target
-Reverse: Reviving is very asked so skill at least to lvl 1 and keep it at Lvl 1 if you plan to do ong farming with this charakter, cause if you skill it farther you revive more Exp with a higher Reverse Lvl
-Innocent: Waste of Sp
-Justice Cross is not needed
-Healing Breath: One Target so dont skill it
-Grad Reverse is only skillable if you achieve Reverse Lvl5
-Integrity is also not needed
+Mental Cure
-Faith: Max it!
+Mortal Recovery
-Over Healing: Absolute Damage, if you plan to job alot as being a cleric, skill it, it bites through all the Defence of your enemy regardless if he is FullBuffed or not, very funny to kill FB Wizzards with it
-Glut Healing: Same as Over Healing
+Recovery
-Group Healing: Skill Only if you got the needed Sp
-Healing Division: Proven to be useful, i skilled it but its not 100% necessary
-Healing Cycle: Useful so skill it (Heals more then Healing Orbit at high Lvl)
-Group Healing Breath: Same es Group Healing
-Healing Favor: Same as Healing Division but stronger
-Healing Orbit: Healing Cycle for the whole party so skill it: Very important!
+Blessed Recovery
-Bless Spell: Skill it!
-Recovery: Dont skill it cause its only targetting one target
-Recovery Division: Useful so skill it!
-Group Recovery: Lifesaver for the partymember with the lowest HP, so skill it!
-Holy Recovery: Stronger version of Recovery > not needed.
-Holy Recovery Division: Stronger version of Holy Recovery, skill it.
-Holy Group Recovery: Stronger version of Holy Recovery so skill it.
+Ressurection
-Group Reverse: Almost never useful, maybe for ongfarming to dlvl 2 chars at once.
-Reverse Oblation: One of those skills which is very important: Skill it!
-Holy Group Reverse: Almost never needed
-Reverse Immolation: Important so skill it!
+Glory
-Charity: Very Important if you plan to be a cleric in parties so you need this skill to open the last line of the cleric tree.
-Glory Armor: If you want to wear LA when you play cleric, then this skill is amazing since its boosts your physical defence.
-Favor Armor: Same like Glory Armor but for magical defence.
+Sacrifice
-Offering: Strongest attack in game, skill only if you plan to be a cleric at FW and GW, and if you skiled the first line in the cleric tree, its fun and useful but not 100% necessary (a Cleric is meant to be a healer and not to be suicide bomber however you can kill TG with one strike with it

.
-Pure Offering: Stronger version of offering.
+Saint Prayer
-Holy Word: I didnt skill it since its only targetting one target
-Heaven Flash: Not needed cause you should be busy with healing anyway
-Holy Spell: Important: Skill it!
-Heaven Glare: Not needed
+Last line is self explaining.
You can choose between LA and Robe, the difference is:
Robe > 20% MP consumption > High Mag Def and Low Phy Def > Higher Movement Speed
LA > 10% MP consumption > Average Mag Def and Average Phy Def > 10% Lower Movement Speed compared to Robe
Also Robe items are always a bit more expensive since every ****** is using a Wizzard, demand and supply is always given here. LA is a bit cheaper in most cases.
If you got further questions feel free to ask.