[quote name='javeryh']
What is the best way to play through the game in order to maximize achievements? Are there any ones that you can miss and never get back too (like some of the audio diaries in the first game)?[/QUOTE]
I just finished it this weekend and got all but 1 achievement (9-Irony) on my first play through (no guide used either).
First you have to play on hard, turn off Vita Chambers and save every little sister (there are a couple other people you have to save as well that count toward an achievement. Advice, just don't kill anyone that isn't a Big Daddy, Big Sister or Splicer and you should be good. *it should be noted* that playing on hard, w/o vita chambers and saving the little sisters is brutally hard early on. Some Big Daddy/Big Sister battles took many restarts and sometimes 30-45 minutes to win, BUT it's
very satisfying when you do finish a battle. You will also run out of money often.
As Salamando said, there is a nice buffer zone on audio diaries, but I'd still recommend being vigilant about finding them. I don't think there are quite 30 extra, I'd say closer to a dozen extra. Enough that allows you to miss a few but not so many as to be lazy about searching for them. Be sure and incinerate all ice "blocks" as well as a few are hidden under ice. Weapon Upgrade stations are fairly easy to find, so finding all of them shouldn't be too difficult.
Basically, just focus on the map and saving. Make sure you visit every room, and every nook and cranny of each room. Places you haven't been to are shaded a different color tan than the rest of the map. Once you hop onto the train to get to the next "chapter" you can't go back, so make sure you have covered the entire map before moving on.
As for saving, save A LOT and keep multiple saves so you can backtrack if need be. I had probably 5 saves per area. When starting a section, I'd make 2 saves. Then as you progress through the level just save over top of one of them and if you
anything up as a last case scenario you can go back to that fresh save before you started doing anything. I would also start a new save each day in case something went wrong I could only go back a day's worth of work. I would also save on the train PRIOR to activating it so I could go back through the level if need be. Yeah, I probably have too many saves, but better safe than sorry, especially early on in the game.
If you are going to try the hard route, good luck. You'll need it.