people aren't used to having to interrupt every single random fireball or holy fire and seeing someone lose 300k hp (when they only have 350k) if they fail to land it or dying to messing up trash mobs even slightly needing to literally chain every defensive in the game to survive a trash pull
honestly, a lot of pvp skill applies to it more than pve skill, such as wisely choosing your cc and your movement as well as playing with LoS and defensives and you'll find people from both crowds doing them
it's a little hard to find a group w/ no xp, but you'll be able to get into more once you have a few down (a lot of groups you'll find will involve people who are 9/9 on several chars, and some like you, who are just starting)
as a frost mage, your high aoe damage as well as 2 raid buffs, lust, ring of frost, a ranged interrupt, and other cc make you one of the strongest specs for CMs on 'em
also try to read through this guide http://www.wowhead.com/guide=1423/ch...in-depth-guide
it also has links to other guides in it, and there are some things in it even I'd consider a bit wrong, but it's a good place to start
some guides and stuff will recommend large chain pulls and whatnot, these aren't really needed for gold in most of them, save most of these to those crazy kids off going for realm #1 times and will usually just wipe people that are new to CMs
and make sure you pick up a lot of int pots and int food as well as some int flasks and invis pots (although if you really want to, you can be lazy and use greater invis as a mage)
changing gear isn't necessary, but it'll help some if you feel like you aren't pulling your weight (especially in regards to getting a spare hat for a non-legendary meta and changing your trinkets)
I mean back when I did them, there were 3 that I 1 shot (lucked into a pug tank that knew what was up), some others took a hour or more of work
and just make sure that when you wipe (which is usually much more likely than not making the timer), you change your plan some for the next attempt
Also check openraid.eu, theres plenty cm pugs going on and always need 1 dps with bl/hero, shouldnt be a problem to join as frost mage at all. Be sure u checked tactic and come prepared with flask,pots. Gl !