How do I mission, and how do I mission my friends into mission'ing?

You gotta find Odessa. He's your gate into the world of missions¹! Looks like that:

That's all I will reveal. You gotta do things on your own too, you know.
Missions are shared, meaning that if someone does a mission, everyone does that mission.

Mission is a set of tasks with a win and a fail condition. They award 50$² on win.

A man with a briefcase will visit the park soon. Odessa wants him dead.
Mission will fail if briefcase guy leaves, or you take too long.

Odessa thinks that his guy is being tailed³(, and for the sake of the mission he is right). Your mission, should you choose to accept it⁴ is to figure out who is the tailer, and eliminate 'em. (Disable, neutralize, dispose of, take out.)

Odessa's guy will try to weed the tailer out by loitering in multiple public spaces. The mission fails if you fail to identify the tailer before Odessa's guy leaves the district again.

• 0 - 'gm_opencity' - Here is the map link, if you came across this guide without knowing about the map.
  
• 1 - 'World of missions' - Only two missions currently available.
  
• 2 - 'They award 50$ on win' - First, I'm not sure that it's 50$, or that it is constant at all. Second, money can be obtained via other means(, literary laying on a sidewalk), and can be used only to buy items in Generic Shop. So it's useless.
  
• 3 - 'tailed' - Being followed by someone.
  
• 4 - 'Should you choose to accept it' - You can not accept a mission by simply waiting until it fails. See individual missions for fail conditions.