9 is still within the realm of manageable game size. I also believe this is somewhat of a mixed skill game, so a newbie isn't out of place.
I'd say the skill difference was much larger in my first game, and I went with Vanarus of all things (like EA C'tis, it's fairly mage heavy nation that rewards people who can manoeuvre the magic system). C'tis isn't the easiest for a newbie to pick up, but I feel that you should first and foremost pick something that thematically interests you. Mechanics can be learned but thematics are what suck you in.
edit:
Criptfeind:
I don't know what you've tried, but you might want to try a few different builds for early game. One with a cheap, high dominion, imprisoned pretender and maxed scales. Other with an awake dom9 dragon with X4 (I'd recommend either the F or W variant).
There are other ways to go about it, but in my experience those are the most straightforward. Scales really supercharge your national assets due to extra gold&resources while a dragon helps a lot with expansion (I won round 408 with LA C'tis using an awake dragon).
The dragon strat is all eggs in one basket kind of thing, so you definitely want to try it a few times to get a good feel for how and what you can take on. While it's technically an early game boost at the expense of later game, the fact that you can emerge as the biggest nation early on effectively makes up for the worse scales you have to take to afford it.
Scales is better if you can pull off satisfactory expansion with just national troops. So you want to try both a few times and compare your performance.
There are other builds with dormant gods and specific paths to achieve certain things, but those two builds are really the most straightforward and simple while still being quite effective.
I would seriously advice against a bless or rainbow build. Rainbows are difficult to pull off with the current game and newbies in particular would struggle to make optimal use of them. Next patch is supposed to reprice the pretenders to make rainbows more viable, but that's in the future. Bless strats are among the easy, straightforward ones, but C'tis doesn't have any sacreds worth blessing so you might as well ignore it.
Some worthwhile research targets for C'tis:
Alteration 6 - Darkness, nerfs most units but demons and undead. Your mages can summon plenty of undead.
Enchantment 3-5 - Raise Skeletons/Horde of Skeletons, the abovementioned undead.
Evocations 5 - Shadow Blast and Stellar Cascades. SB costs a gem to cast and if it fails to break target MR it does nothing. On the flipside it has a huge AOE and you can forge spell focus and void eyes for a D4 sauromancer to boost their magic penetration. Also note that while humans have base MR 10 (Ulm have only 9), most fantastic races have higher. So it's situational, but if you end up fighting a human nation, consider shadow blast.
Stellar Cascades is spammable by your S1N1 mages (either communion them or have someone cast Light of the North Star). Cascades does irresistible fatigue damage with a decent AOE. It doesn't kill anything by itself, but fatigued units are easier to crit among other things. (I had a lot of success with massed S2 mages spamming cascades in round 402).
Thaumaturgy 1 - the abovementioned communion master/slave spells.
Do note that I've never played EA C'tis, and I've only played one games as LA C'tis, but those are some basics you might not be aware of.
Oh and if you're not aware of it, there's this tool (I know it's in the OP, I'm assuming no one reads them):
http://larzm42.github.io/dom4inspector/It's basically a web browser based civpedia. It has all the items, spells and units (filterable by nation or other parameters). Very useful reference tool.