I'm not a sorc expert, but I do know that by and large, zero block is just asking to die.
Actually, medium-high (or higher) block with a crappy-blocking shield (like Spirit) is more of a recipe to die, IMO.
You're life is likely to simply be so low that you're stuck in hit recovery any time you don't block an attack, and every blow received will take a relatively high percentage of your life. With Spirit, IMO you should say "to hell with blocking! I need life."
... that's my opinion, of course. Others differ.
*****
I've done 3 different CL-based sorcs (2 FO-variants, and a level93 Firewall variant as one of my first serious D2 builds). I'm not volunteering to write a guide, but here's some basic pointers from my experience:
Early Game:
1. Lightning and (especially) ChainLightning are mana-hungry spells. If you want to go with a lightning attack early in the game, you'll want to focus a lot effort on +mana, +mana regeneration, and +mana per kill equipment (3xPerfect Sapphire helm and armour, Manald Heal rings, Insight merc, Lizards/Snakes/Serpent charms, Tir runes in your weapon/shield, etc.)
2. Likewise, Frozen Orb is powerfull enough that many people recommend that you focus on maxing that as quickly as possible (with one point in CM)... and then use FO as your main killing-skill through Normal and NM difficulties, while you're building your lightning skills for hell difficulty. About the time that FO starts to really slow down in late NM, your lightning skills should be really starting to shine).
3. because CL is such a mana-drainer, I prefer to focus more on Lightning during the early stages - Lightning takes about 50% as much mana as CL, and Lightning does roughly 100% more damage than CL (by average). If you're working with FO already, that means you already have a good crowd-killer. And teleport is still one of your best crowd-control skills anyways, so you can definitely get away with a low-level CL for a long time.
4. Generally, during the early game, increasing your overall mana pool is more effective than increasing your mana regeneration. Once you get a large mana pool, mana regeneration starts to perform better (I don't know where the cut-off is though).
Blocking vs. No-Block.
... the eternal debate. Use the search function for the previous 1673 discussions on this, since all of valid points have been covered quite extensively... there's no point in hijacking another thread with more on this, and I'd be just as content if any guide took this stance as well.
The Countess:
I already wrote a detailed guide about dedicated Countess running, and a large portion of the guide is focused on running with a CL/FO sorc. The guide is focused on single-player, but I'm confident I didn't omit anything of significance in regards to Countess runs with this build. The guide:
http://www.purediablo.com/forums/showthread.php?t=536471
... there's more, but I'm already loosing interest in CL/FO sorcs again. They're definitely a fun build, and very viable PvM with even modest equipment.