Plans will change. The primary raid goals will not always be available. Be flexible as there may be backup plans you didn't plan on. It's hard work planning a raid and even harder when you have to change plans in midstream. This is critical.
People waste real life time waiting on others.
It shows real disrespect for your fellow guildmates. Also arrange your own ports, and only after trying and failing bother a raid leader with port details. Please be at THAT location at THAT time. Being late to start will lead to you being counted as late for loot purposes. In addition, attendance for weekend raids is as close to mandatory as it gets.