Just from my own personal experiences when playing online games, I try to focus on what I am doing, and let the other group members just play how they prefer to play their role. The only time I feel comfortable making suggestions to someone is if the group is not doing very well. Even if it takes a few more minutes to clear the zone, as long as we are not getting killed, I'm not complaining.

And when people have given me tips and tricks on how to play my role in mmorpg, iv always appreciated the ones who waited tell the group was over, and then sent me a private message. So as not to possibly embarrass me in group, as well as giving me time to ask questions or go into a more detailed strategy without holding up other people who were in the group.