Do you eventually get enough points to get all of the augments or do I have to be stingy and only get things that are crucial?
edit-double post whoops.
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According to one of those load screen messages, you can't get them all in one playthrough. You won't even need to spend all your praxis to beat the game though, just upgrade hacking capture & stealth all the way, move heavy objects (for shortcuts) and play around with the rest. My personal faves are the leg upgrades, specifically the jumping and silent footsteps.
There are a lot of useless upgrades, so there are enough praxis points in the game to get all of the "best" upgrades. And there are only two "builds" possible-- stealth and frontal assault. But half-way through the game, you'll find yourself putting points into the upgrades for both, because you'll have that many points to spend. And to only put points towards one or the other is gimping you in-game. It's not a game designed for "builds".
In conclusion: there are no builds, and you can get most upgrades in one play-through.
There is a guide to maxing XP on the DX wikia, but for the most part you'll end up a few points shy of learning everything. It's not particularly hard to get all the ones you want, it's more a matter of what order.
Meet Gabriel Belmont and his Vampire Killer!
There is the no upgrade build. This is my favorite. The no upgrade ghost run is my favorite play-style.
Rule 2, ignore rule 1.
You can do weapon builds as well to diversify your combat runs. There are a lot of builds you can create & play if you want.
Does the hacking trick still work on Adam's work computer? If it does you can max out all your augments right at the start of the game. It is fun for a minute. It takes a lot of time though.