Private to James/Harry
Think like a cop. Assume anyone you meet is a threat. Always be ready to fight. Don't let your guard down. And for fuck's sake learn everything you can so you can be prepared for when you're right about someone.
If they want you you aren't any safer inside or outside of the school. No one is. If they want to eradicate muggleborns or whatever the hell it is that they're after, then they're going to do it no matter where you are. It's better to be with those you love, knowing they're safe, knowing that you are there to keep them safe, rather than wondering what they're doing or where they are or what's happened to them.