If you are driving on a motorway where I am driving too, here are some rules you should follow. I think you should even follow them when I'm not around.
- Be sensible, this one overrules all the others
- Keep left unless overtaking
- KEEP LEFT UNLESS OVERTAKING
- KEEP LEFT UNLESS OVERTAKING
- Always indicate when changing lanes
- Pick a speed and stick to it, avoid speeding up or slowing down whenever possible
- Be courteous, even when people make mistakes
It's not that hard, try it and you'll realise traffic would be a lot more fluent if everyone stuck to these rules.
PS: Don't forget to substitute left with right depending on your country.