Since there probably are as many ways to finish a mission as there are players, I wont go into detail on how to do it. I'll just describe what you need to do to complete the missions. Also, you dont have to do the missions exactly in the order I did them. I will tell you when a mission has been unlocked even if I continue with some other mission.
A good rule when you do any mission is to get as good weapons as you can and armor if possible. This will make a lot of missions easier to complete. Everything you need to find, both where the missions are and what to find/where to go once you do them, will be clearly marked on you map so you wont find any screenshots for the missions.
Note! Do not park next to a wall and get out of your vehichle. You might end up inside the wall like I did :)
Have fun, and good luck...