Well, i guess by this time now, you should be able to tell whether a fry is dead or not
If not, just use the baster to move near it to create a bit of current and see if it'd move. The dead one will just 'float' with the current.
It takes time to learn the skill for not sucking up live babies. I've tried many different ways, but the best way I found now is use a thicker tubing to vacuum the bottom.
Like Iggy says, try to avoid doing anything for the first few weeks. After that, the fry should get bigger and smarter, and they would know where to hide when you vacuum the tank.
Having said so, even now I still suck up fry once in a while. That's why i prefer having a wider tubing, so the fry can easily be sucked up to the bucket. (rather than getting stuck in the tube and died). Then, I'd just put the poor fry back into the tank from the bucket. THey may feel a little dizzy... but they seem ok afterwards.