Bossing Around Informally

This time, as with every other project I've ever been a part of I have taken the heave responsibility for it's completion. I think I lay this on myself every time not because I don't trust the other people I work with but because I cant handle not to have full control over my own situation.
In addition I believe that the rest of the group allows me to do this due to the fact that this way allows them to relax knowing that someone else is taking on the responsibility.

That aside, how can I "boss" people around in an informal group where no one has elected anyone as leader without pissing anyone off? I won't say I've got a final answer to this, but I have made me up some thoughts.

For instance we had a situation where a few of the group members were really hellbent on going in one direction while me and my co-director/producer Adrian immediately saw that it was the wrong way to go. Unfortunately there was no way of turning them without using a direct order. And that was something I wasn't prepared to do. So instead of battling these guys further we actually went along in their direction until another more concrete and better solution could be worked out. In the end everyone was happy and we avoided any bad feelings during production.

We also had an issue with people coming in late or not turning up without letting anyone know what was going on. So I made it a rule that if you weren't going to be on time you had to report it in our forum online. This actually proved to be very effective as I now suddenly knew where everyone was and what resources I had at any given day. It goes without saying that being on time and calling if you aren't is the norm in a studio but this isn't always the case at a school. 
In this case I used a direct order even though as a informal leader of a group I really shouldn't do this. Nevertheless I got away with because it was a reasonable demand that everyone either already agreed with or felt like they had to anyway. 

Bossing informally is hard because you can't always act as the boss and demand things without explaining why and your authority is constantly challenged. You have to stay at the top of your game at all times.