Always upgrade on the fly
With the exception of having a crew present to roam the streets of Gotham, the second most important thing you need to do is always upgrade your inventory. As you acquire accessories through killing enemies or helping the poor in need with water, food or medical aid, your stats are always increasing. Not keeping an eye on your new abilities and inventory, will cause you to have inferior weapons, armor and essential any piece of gear when going up against a human or cpu enemy in battle. Upgrading from a level one protective vest or gun, could be the difference in you surviving the dark zone or a non-re-spawn area in the regular campaign.