When to use your Character Markers
You're in a combat situation which has your character at a considerable distance away from others. You set one up to keep a physical representation of your character while you're gathered together with players who have also placed their markers somewhere in the distance that is at least twenty meters out.

When NOT to use your Character Markers
When you're all IC'ly clumped together and within twenty meters of each other, so you might as well just use your avatars anyway unless your character is going to move out of chat range.

Thank you.