First of all to spot an enemy player you double tap v. This makes that player show up only on your team's mini map to see. He could either show up as a red dot or a red version of friendly player icons on the mini map right now.
In example :

The enemy spotted disappears after 5 seconds, then he needs to be spotted again to show up on the mini map again.
The person who is spotted will also be notified. If you are spotted your little med pack will turn orange and a red exclamation point will show up next to it. The contrasting colors will hopefully catch the spotted players eye so he can take action.
In example:

This addition would add more tactical game play to AoS as well as boost teamwork in public games. Many snipers will have to be sneaky in order to survive.
Please discuss this idea and how you think player spotting should work or if it should be implemented at all. I would also like to thank Kukelekuu for helping with ideas for this suggestion. If you ever see him in game please give him a cookie.