Where every 'mistake' is a learning opportunity.
There will be test works to critique as practices, and mentors who will guide you through any mistakes you may or may not make. I'm not saying that our way is the way, but it is a way to help you get started before you branch out into your own style.
Firstly you need to decide whether you wish to learn to critique poetry, prose or both, as different admins deal with different forms of literature. Once you have decided, note the group with your choice and we will begin your training.
Note: You will be trained by whomever in the way that they personally like to complete critiques. Feel free to adapt the style to suit yourself once you know the basics.
Also, once you are confident in your critiquing abilities, I encourage you to join a critiquing group, such as GrammarNaziCritiques or SuperWritersHelp (I am sure there are more but those are the only two I know). This will help the group, as critics are always needed, but it's also a chance for you to practice your new skills so that you don't forget what you have learned.
Please don't just join and lurk. I'd rather have few members who want to learn than millions of members who lurk.
Have friends who want to try critiquing but don't know if they have the skills? Invite them to join and try out the group.
Any questions? Note MagicalJoey