Considering some of the earlier confusion about how cover works, I came up with this little idea. To get cover you have to use one of two "Take Cover" simple actions, either partial or good cover.
If the cover can only cover 25-50% of your character, you can only use the "Take Partial Cover" action, to get a +2 to defence, this bonus lasts until you move out of cover (or the cover is destroyed), and you can attack as normal from this position, with no penalties. The is the character peering out of cover, ready to fire, while still protecting themselves.
If the cover can cover 50%+ of your character, you can either "Take Partial Cover", as described above, or you can "Take good cover" which applies a +4 bonus (plus concealment, if your whole body is concealed), this bonus lasts until you move out of cover (or the cover is destroyed), however you can only attack with blind fire (or anything that lets you attack around a corner) while in this mode). This is your character covering as much of their body as possible, while firing by sticking their gun out and pulling the trigger.
Switching between the two is a simple action.