I always look for ppl with experience, because most of the time I'm not in the mood to explain the tactics for strangers. With my friends we are mostly communicating on TS, I explained dungeon and raid tactics a dozen times already. If you would like to learn, the best what you can do is to join a guild and ask ppl to help or go online, check the tactics and watch some videos. But if you see someone looking for experienced players, be respectful and don't join if you have no idea about the dungeon or raid.