I don't know, but I have to give you a warning. Most Angels don't see us friendly... They're most likely to harm you and in some cases seriously. They may try to possess you.
Invocation is inviting the spirit into your body... It's not possession, these are very different. I suppose you already know that, before asking. Evocation is summoning of the entity but not in your body. For beginning I suggest to do channeling-with the idea you're looking for an invocation. Channeling isn't the same thing as invocation, I just suggest it as a beginning...
I know three ways to channel entities. First of all, close your eyes and clear your head. Try to focus on the Angels's sigil..after a while you may feel a headache or different sensations. Secondly, clear your head again and call for Angel's name. Lastly, clear your head and try to visualize the Angel.
I don't know how will you communicate in these ways, I haven't studied channeling. Many people say you should have a piece of paper and write your questions with your dominant hand and then to see the answers, take your non-dominant hand and write on the paper whatever comes to your mind. Others see the entity normally (with closed eyes) and they're able to hear them. I suppose the last method requires these two psychic abilities.
I don't think you should speak Enochian... Most Angels know many languages and I'm not saying all of them because I haven't meet all of types personally (I haven't meet any type).