Easy x50 Combat Combo
You can make the "Free Flow Fifty" achievement easier to get by jumping over your opponents' heads after you attack them. That way, it is more difficult for them to break your chain. The best place to try this is in Round 4 of Intensive Training. You should be able to get a x50 combat combo. If you can use the Shock Gloves, they will make it even easier, due to their x2 multiplier.
Instant 120,000 XP Glitch
You can get 120,000 XP at the start of the game if you take advantage of a glitch at Burnley. Go up to the roof like you're supposed to, but let the enemy kill you to create yourself a checkpoint just before you reached the roof. When you respawn, grapple to the roof again, but this time take out three enemies with silent takedowns, and finish the fourth with a silent takedown and a knockout smash. You'll get 8,000 XP and the game will save, but after the Save icon disappears, you can still restart from your checkpoint to repeat the process and stack up the XP.
Pinkney Plaques Location Guide
This game features an optional sidequest in which you have to seek out eight Pinkney Plaques and scan them with your detective vision. The plaques are located at the areas described below.
Old Gotham Cathedral - Park Row: It's on the back of the church's tower. You will need to climb to the roof to find it.
Solomon Wayne Courthouse - Park Row: It's on the back of a horse statue. To reach the statue, start at the courthouse and head west.....