first rule is to just equip the best gear you have at the time. Run all the story missions consecutively. That should get you to level 27. Bang the last 3 levels out doing side missions and not encounters. Focus your base leveling as much as you can into 1 wing. Fill the other wings out during end game. I hit level 30 in 24 total hours of gameplay. Forget the dark zone until you hit 30. Soon as you walk into the dark zone at level 30, your first few kills will rank you up 3 DZ levels. Save your credits as much as possible too, level 30 weapons from the advanced weapons dealer cost over 100K credits. I saw an Elite Assault rifle in there for 400K.