Hi Sebastian
If you want to change the colour away from green try:
Tools ==> Options ==> Themes & Formatting ==> Edit ==> Task Format ==> Active Tasks Format ==> Font ==> Font Colour
But reading your email more closely it does sound like Start Date is the way forward.
If the Start Date is in the future then the task will no longer be "Active".
And if your view is set to only show Active tasks then those tasks should disappear from view.
Try: Filter (bottom left) ==> General ==> Show Actions: ==> set this to Active.
Alternatively as others have said, you could so some Automatic Formatting.
e.g. If Context contains @Wait-For, then change the colour (e.g. to mid grey?)
Hope that helps
J
PS I use Active task views and Start Date A LOT. e.g. By just using the keyboard:
Alt+S 5 D
==> Moves the start date 5 days into the future.
Alt+S 3 H
==> moves the start date 3 hours into the future.
This gets things out of the way until I need to chase things up. Good luck