Take your pick of the following :-
Why you should read apricotslice (managing editor) 's manual, and possible uses for the original manual (how to make it softer/more absorbant and put perforations in it)
Tractor Beam Guide (stuff you can tow, stuff you can't, pushing, getting a lock, SETA and speed settings, how to get something to a specific position)
Pro's and Con's of Complexes vs Individual Stations & Traders
Station management screen
Complex management screen (epecially the 'buy intermediate products' - does that mean "I will buy" or "I will let NPC's buy" for example and the pro's and con's of using this)
Ship Guide, I'm sure Roguey won't mind if you give him credit
Weapon Guide, description of uses.
Equipment Guide (SETA, I can't believe the number of people who think this speeds up the game ! instead of slowing your perception of it ! The pro's and con's of using it ! (and how to change the SETA factor))
Laser Towers (the most useless piece of junk in the X Universe apart from the ecliptic projector)
Docking Computer (Why it's a good idea !, until they remove it in X4 (hopefully))
Scanners and the scanner display, how to read it/use it
Software Guide (what everything does/is used for)
Surveying Asteroids, Yields, Mine Sizes (and what that means)
ST & UT Guide (your own is the definitive I believe)
How to use a Jumpdrive and 5 ECells (when in a fighter) to find ANY gate ! (Jump Sector, Move Position)
Brief mention on scripting (what it is, how to activate, where to go for more info) but we should be concentrating on the vanila.
A list of links to Spoiler information (let them choose) e.g. Map, Free Stuff etc.
Example bugs :-
Why can't you use '5' & '6' in an assets management screen
Why there is no laser energy display (if there is, I've not found it !)
ALL the other stuff I've ever seen you discuss in threads (you don't need to rant (like I would) just list them with a suggestion of how it could be better) We should always strive for perfection but realise it's attainment may require a considerable wait !
Well these are the things I wish I'd known when I started the first time !