From an artist's standpoint, it can be quite daunting picking up a new VFX heavy project, or any project where you’re not really confident in your skills.
Perhaps rigging is not your forte? Or maybe you’re not up to speed with the latest particle goodness?
That’s okay.
The best thing to do is ask someone who knows, breakdown the problem into smaller problems and tackle them individually or find local solutions. Look at it from a different angle, perhaps the problem is not what it appears to be.
Can you cheat? Often times doing seemingly simple things in real life are an absolute pain in the rear in CG, take ages to develop and still don’t look quite right at the end, consider cheating, use real footage for example or do it cheaply in post where it’s possible.
Try multiple things at first, keep them quick and rough until you find the solution with the highest potential to do the trick.
The point is, be flexible, set things up in a way that’s easy to change until parts get approved, then build on and improve them.