If you want to increase your chanse for a spot in the raids, here is what you need to do.
Don't ask for a spot. we will invite when Gmotd says we're starting
Be active. If you are not able to raid 3 days a week, you will probably be a backup for someone in the raid.
Have a PvE specc. Ask a Veteran(or higher) ranked player of same class if you have any questions for your build.
Be on time when raid invites start, and only go afk when the raid leader allows it, or you have a good reason and have told the raid leader.
Always be full repaired and having pots* with you.
got questions? ask a veteran ranked player
*healers should bring 10 mana pots
otherwise just have elixirs with you needed for your class!