In order to complete both story lines in a single play through as detailed at the top, there is one important point. At the point, early on, where side missions are introduced, "Karma's A Bitch", you must choose the EVIL mission. If you choose the "Good Samaritan" mission, then you will lock out the Evil "Taking Out the Trash" assassination mission. You need this mission to get the Evil "The Cleaner" trophy. Choosing to do the evil mission has no effect on subsequent missions or Trophies, as "Good Samaritan" is not used for a Good trophy. It's worth taking the small Evil XP hit on a good run, just to keep the trophy open. You'll have plenty of chances to earn Good XP to offset it.
You can use the blast shard bombs to get big evil karma by shooting the bomb, which creates an explosion that will kill everyone caught in it. I think it may be an instant kill for anything in the blast radius, as I shot one when a Hive Lord was next to it and it gave me an insta-kill on it. I will attempt to get one on a devourer, but if anyone else wants to try it would be muchly appreciated
For Headhunter it seems you do not need to get three separate headshots on three separate enemies.
I was doing The Dunbar Beam mission and when it came to the part where you need to fight the ice duo, I used precision and got 3 headshots on one of them before he died. After he went down the trophy popped. So it seems you just need to make the "Precision Headshot" reach a 3x regardless of how many enemies it took.
Of course this could already be common knowledge, if so, disregard this xD
Could You Say That You Can Do Them Both Offline. In The Cheats , Glitches and Exploits Section
Going To Do This On My Back-Up PS3 Because I'm Halfway My Evil Playthrough (Hard) after Finishing My Hero Playthrough On Easy
Do You Have any Hints for The 'Knockout in the Blackout' Trophy . It's Really Hard! (Easy Difficulty)
Finally , Would You Recommend Using A UGC Mission By Bobzilla24 For The Blast Shards?